While a vessel was navigating the Pacific Ocean, the duty officer noticed sparks coming from the main engine funnel. After a short time, the Exhaust Gas Economizer (EGE) gas outlet high temp alarm activated. It was acknowledged as an EGE fire and the crew started reducing the main engine RPM and stopped the engine.
After approx. 8 hours of cooling down period, the crew opened the inspection door of the EGE and found extensive damage to the tubes, tube support, and fins of steam generator (upper). Some of the tubes had cracks and were deformed, and the fins were melted. A temporary repair was carried out. However, a large scale permanent repair at the is needed.
It is suspected that inefficient soot blow caused soot accumulation on the tubes resulting in a soot fire because the vessel carried out soot blow by 28k air pressure WITHOUT increasing the engine load.
Suggested preventive measures
1) Removal of soot - Increase engine load when carrying out soot blow while navigating at slow speed, and regularly carry out soot cleaning (water wash or air blow). Soot must be completely removed if water washing carried out because self-ignition point of remaining wet soot is lower than dry soot.
2) Observation of soot - Confirm no soot accumulation on tubes by opening the manholes at regular intervals and monitoring the operational data on a daily basis (EGE draft loss, outlet temperature, steam dump valve openings, T/G available power, etc.)
3) Reduction of soot - Keep main engine combustion in good condition by appropriate management of fuel injection atomizer, including proper fuel oil pre-treatment.
4) Cooling down of soot - Ensure boiler water circulation pump working in good order at daily checks.
Immediate action required at initial stage of soot fire
posted 26 Jun '17, 01:45