Burner Regeneration
A diesel fuel burner is placed in the exhaust in front of the filter to regenerate the diesel particulate filter. This system can perform at all engine speeds and loads. Two types of system have been used;
- burner full flow system and
- burner bypass system
In the full flow system the total exhaust gas is to be heated to about 540º C. A large air pump for the burner and high burner fuel consumption are needed. Complex electronic controls to regulate burner fuel flow to maintain safe levels of gas temperature at inlet of filter are necessary. In the bypass system, only a small part of exhaust is allowed to flow through the filter when regeneration is carried out. A smaller air pump is required. A bypass burner regeneration system is shown on Fig 6.16. Regeneration process is independent of engine operating conditions, as the filter during regeneration is isolated from the engine exhaust. The fuel consumption by the burner to heat the inlet face of the filter to 540º C is an order of magnitude lower compared to the full flow system. The relative magnitudes of energy required to raise the exhaust temperature to 540º C in the full flow and bypass type burner regeneration system (10 % of total flow) are presented in Fig 6.17 for a 5.7 liter diesel engine.
 |
| Figure 6.16 |
Schematic of diesel-fuelled Burner Bypass Regeneration system for Diesel Particulate Traps |
The inlet face when heated to 540º C, soot oxidation begins. Increase in temperature of the gas accelerates combustion of soot further. The burning process progresses from the front and oxidizes soot in the remainder of the filter.
|
