Emigreen® soot reduction systems use a monolithic ceramic filter that is extremely efficient at capturing the soot particles emitted by diesel engines. To optimise filtration efficiency and extend the operational life of the filter, the particulate matter that builds up in the filter has to be removed. The process of burning off the accumulated soot is known as filter regeneration.
Filter regeneration involves heating the filter to a high temperature. In engines with sufficiently high exhaust temperatures, the exhaust stream contains enough thermal energy to initiate and sustain the regeneration process. This typically occurs with engines operating under load for a sufficient length of time.
If the engine runs on low sulphur fuel and the temperature of the exhaust stream is sufficiently high, a catalytic or self-regenerating filter may be suitable. This type of filter regeneration is referred to as passive regeneration.
If the engine fuel contains 0.1% sulphur or if the temperature of the exhaust stream fluctuates, it is necessary to introduce additional heat to ensure that the filter regenerates.
To supply the additional heat needed to elevate exhaust temperatures to the required levels, the exhaust system can be equipped with a burner. This type of burner-assisted regeneration is referred to as active regeneration.
The Emigreen Delta is a passive (self-regenerating) system. The Emigreen Alfa Alfa is an active system that uses a burner to create the heat required to regenerate the filter.