DPF passive (NO2)

Passive regeneration by means of NO2 use (CRT – Continuous Regenerating Trap)

In passive regeneration, nitrogen monoxide (NO) is oxidised to nitrogen dioxide (NO2) on a catalytically coated surface. This additionally generated NO2 reacts with the soot particles from temperatures as low as approx. 220°C. The soot is oxidised and the NO2 is reduced back to nitrogen monoxide (NO). Exomission offers various coating technologies in order to restrict or increase the desired NO2 concentration specifically for different customers. The particulate mass reduction of the filter systems is significantly over 95%. The system is usually operated with a data logger to monitor the temperature and pressure.


Passive regeneration by adding additives (FBC – Fuel Borne Catalyst)

The Fe-based additive is responsible for lowering the soot ignition temperature. Usually, an exhaust gas temperature of approx. 600 °C has to be reached so that the soot can react with the oxygen.

Adding/apportioning the additive to the fuel means that the soot collected can react with the oxygen from a temperature as low as 400°C. This reaction may not be as fast as for the standard oxygen burn-off temperature, but is still much faster than the CRT reaction using NO2. When using additive-assisted regeneration, the sulphur content of the fuel is unimportant. This makes applications which would not be feasible with standard coatings possible. A significant disadvantage, however, is the increased ash deposit by the additive. This means shorter cleaning intervals for the operator. This technology also has the advantage that the NO2 emission is generally not increased.


DPF active (HC dosing)

Fuel can be injected into the exhaust gas system in active regeneration by means of HC dosing. The fuel is oxidised in an exothermic reaction on the catalytic surface. This increases the exhaust gas temperature to approx. 600°C. At this temperature, the collected soot can be ignited and the filter regenerated as a result.


DPF active (burner)

Another regeneration method is to use a burner system.

Burner regeneration can take place as stand-alone regeneration or in addition to passive NO2-assisted regeneration. If the passive NO2 regeneration is not sufficient, the burner is activated as needed. Using the regulated burner means that the exhaust gas inlet temperature is unimportant. Due to the exact regulation and tuning, the filter inlet temperature can be monitored, thus making it possible to protect the components. If stand-alone burner regeneration is used, the sulphur content of the fuel is insignificant. This also makes applications which would not be feasible with standard coatings possible. In addition, this technology has the advantage that the NO2 emissions do not normally increase.



Due to ash deposits, the particulate filter and/or the filter module require maintenance or cleaning at certain time intervals. These intervals depend on various factors (e.g. oil consumption, quality of the engine oil used, regeneration strategy, etc.). Depending on the operating mode, oil consumption and the filter system used, typical cleaning intervals are one to two years. Increasing back-pressure indicates that cleaning is required. For this reason, the filter systems are supplied with our data logger to monitor back-pressure. A “critical” back-pressure is preset, so that the operator receives an indication of the upcoming cleaning in good time. Exomission provides comprehensive service in this area: Contact us, and we will organise the rest! You will have your cleaned filter back in operation in a few days.


Background information

The wall-flow filter is a ceramic substrate and is composed of silicon carbide (SiC) or cordierite depending on the application. The canal structures can be laid out asymmetrically in a honeycomb pattern in order to achieve the longest possible maintenance intervals.

Particulate filters are perfectly suited for retrofitting. Almost all geometric shapes can be realised in this way.

Simple replacement – in the form of an intelligent exchange system – also predestines the particulate filter for use in the stationary engines area, e.g. CHP.



DPF sizes (round)


DPF sizes (square)


Shell shapes

Standardised particulate filter connection options:

Particulate filter

a) Axial-axial


b) Radial-axial


c) Axial-radial








d) Radial-radial


We look forward to hearing from you.




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