202535 Incinerator overheats

From rags to riches...for the repair yard: An incinerator’s tale

An engineer was charged with burning garbage and oily rags in the vessel’s incinerator. At one point, smoke emerged from the exhaust pipe, accompanied by excessive vibration in the draft fan. The engineer in charge used a dry powder extinguisher and the water mist system was automatically activated.

Crew members were alerted, and firemen stood by. Once the smoke was eliminated, a thorough inspection confirmed the exhaust piping, expansion joints, and gaskets were intact with no fire brick damage. However, the draft fan’s impeller sustained severe damage, causing imbalance in the unit

It was later determined that during the burning of oily rags, the incinerator temperature increased significantly, triggering a Flue Gas
Temperature (FGT) High alarm, which led to the unit automatically tripping. The flue gas fan continued running to cool down the furnace until the temperature dropped to approximately 170°C. During this cooling phase, excessive vibration in the fan reduced the furnace draft. This resulted in localised overheating of the exhaust pipes and furnace, causing insulation material to produce smoke, which subsequently activated the fire alarm and water mist system.

Lessons learned

• Disposing of high-temperature waste (such as oily rags) via the incinerator can lead to unexpected issues. Strict monitoring and controlled burning practices should be employed.

• For example, a controlled burning process for oily rags would ensure a small number of rags are fed and continuous temperature monitoring is employed to avoid rapid overheating.