Combination of Different Regeneration Methods for Diesel Particulate Traps 980541

A particulate trap with additive supported regeneration is a very effective way of reducing soot emissions of diesel exhaust gas. Particulate traps presently available on the market clearly show that the regeneration process is the most important detail in particulate trap technology. In this specific case of particulate traps, active rare earth oxides are added into the fuel to produce an initial and almost continuous regeneration without external burners, resistance heating, etc., as is well known from other systems. It should not be forgotten that an externally initiated regeneration will always produce a temperature peak inside the soot collecting filter media which may destroy them. Such damage can be avoided by catalytically supported regeneration of particulate traps. In the presence of an active catalyst, an inorganic cerium compound, regeneration temperature will decrease from 550 to 600 deg. C normally to about 350 to 400 deg. C.

Exhaust gas temperature of modern turbo-charged diesel engines is very often below 200 deg. C during urban traffic. Hence, the passive method with fuel additives is not sufficient to provide trap regeneration during such continuous low engine speed/load conditions. The active trap regeneration process (e. g. with diesel burner and electrical heating of exhaust gas) is very expensive and energy-consuming.

This paper explains possibilities for the development of a particulate trap system for many applications, and shows the advantages of combining different regeneration methods for particulate trap systems.