Catalytic Bypass Burner - CB²-System

Diesel engines can be found in a huge variety of applications commonplace throughout our daily lives – just think trucks and cars. But they unfortunately emit poisonous particulates while doing so. Thanks to HJS diesel particulate filters, however, these emissions can be almost totally eradicated. If these filters are to work properly long term, they need to be regenerated from time to time – in other words, the soot particles trapped by a filter have to be burnt off in an eco-friendly way. The problem with many applications, however, is that the temperature of the exhaust gases is too low to trigger the regeneration process.

It's precisely for this type of application that HJS has developed its CB2 system that guarantees filter regeneration even when exhaust-gas temperatures are particularly low. And that

  • without assistance from the engine
  • without additives and
  • without increasing NO2 emissions

Catalytic Bypass Burner - CB2-System

Catalytic Bypass Burner
Das CB2-System ist selbst bei sehr niedrigen Abgastemperaturen geeignet. Video anzeigen ...

Catalytic Bypass Burner
Catalytic Bypass Burner

System components

HJS's CB2 system comprises a diesel particulate filter, a primary catalytic converter (DOC II) – that basically generates the heat required to regenerate the filter – and a preheating unit. The function of the preheating unit is to bring the primary catalytic converter up to operating temperature. The preheating unit comprises a diesel oxidation catalyst (DOC I), an electric heating element and an HC doser. The electric heating element brings DOC I up to operating temperature when the exhaust-

gas temperatures are particularly low. The HC doser doses and injects diesel into the exhaust gases in a controlled manner in order to use the two diesel oxidation catalysts as catalytic burners. The diesel fuel oxidises in these catalysts and releases heat. The exhaust gases in the primary flow section and in the preheating unit are controlled and directed in line with the required operating conditions by means of an exhaust flap built into the primary flow section. The HJS Aftertreatment Control Unit or ACU monitors the operating conditions and coordinates interaction between the system components.

Regeneration process

The filter holds back the diesel particulates. When the filter load limit is reached, the regeneration process is initiated fully automatically by the control unit. Firstly the preheating unit is briefly purged and then the heating element activated, if necessary. Once DOC I has reached its operating temperature, the fuel dosing system injects diesel, which combusts and releases heat in DOC I and brings DOC II up to operating temperature. By deliberately increasing the amount of diesel injected, the diesel added can no longer be fully oxidised in DOC I and it "slips" through DOC I uncombusted and into DOC II. The uncombusted diesel enters DOC II, where it oxidises and heats DOC II and the filter to approx. 600°C, regenerating the filter completely in the process. The ACU monitors the regeneration process, detects when it has been completed and returns the system to its normal operating mode. A new load phase begins.

Temperature curve during active regeneration
Temperature curve during active regeneration

HJS's CB2 system is a very effective system for regenerating diesel particulate filters when exhaust-gas temperatures are low. Deployed in a wide range of applications, HJS Emission Technology's innovative products are playing an active and sustainable role in protecting the environment and people's health. What's more, they ensure diesel-powered vehicles and machines comply with all statutory emissions requirements, while also improving their economic performance.

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