Soot-fire accidents in exhaust gas economizers (EGE) represent a major risk due to the potential damage. Various factors such as heat transfer, soot deposit, soot calorific value, spark load, and flue gas velocity contribute to the start of a soot-fire. The rise in soot fires in recent times is related to the general poorer fuel quality and often linked to a specific low-grade bunker. The increasing use of low-grade fuel results in higher soot levels. If the cleaning intervals are not adjusted accordingly this will increase the soot fire risk. Such a fire may develop in three steps:

•  Soot burning & heat accumulation

•  Steam build-up, steam blockage, and loss of heat exchange

•  High temperature oxidation of surfaces and meltdown of the EGE.