(a) Feed Contamination by Oil from Heating Coil Drains

Prevention Measures:

• Ensure heating coil drains are led to an observation tank or inspection glass before discharging overboard, so oil presence can be detected.
• Provide and maintain steam traps and drain valves in good condition to avoid oil leakage into feed systems.
• Fit non-return valves and isolating valves between heating coils and feedwater system.
• Regularly inspect and test coil integrity to detect leaks early.
• Avoid direct connection between heating coil drains and feedwater system without monitoring arrangements.

(b) Internal Corrosion

Prevention Measures:

• Maintain correct boiler water treatment program to control pH and dissolved oxygen levels.
• Use oxygen scavengers and chemical dosing as per manufacturer’s recommendations.
• Maintain feedwater temperature in the cascade tank at about 85°C to aid oxygen release.
• Keep feed tank and cascade tank lids/manholes closed to prevent air ingress.
• Carry out regular blowdown to remove sludge and maintain proper alkalinity.
• Inspect internal surfaces periodically and renew protective coatings if applied.

(c) Furnace Blowback

Prevention Measures:

• Always carry out proper pre- and post-purging to clear combustible vapors from the furnace.
• Maintain correct air–fuel ratio by ensuring proper functioning of air dampers, fuel regulators, and controllers.
• Inspect and clean atomizers/burners to ensure fine fuel spray and complete combustion.
• Check fuel viscosity and temperature to maintain correct atomization.
• Avoid ignition attempts in a furnace containing unburnt fuel; purge thoroughly before re-lighting.
• Ensure proper sequence and interlock functioning in the burner management system.

(d) Uptake Fire

Causes:

• Accumulation of oily soot on tube surfaces due to incomplete combustion.
• Poor circulation through tubes causing overheating.
• High tube metal temperatures (>700°C).

Prevention Measures:

• Carry out regular soot blowing and periodic washing of exhaust gas boilers to remove soot deposits.
• Maintain proper air–fuel ratio and ensure complete combustion by checking damper and fuel control systems.
• Ensure adequate steam and water flow in generating and superheater tubes to maintain good heat transfer and circulation.
• Keep auxiliary blower running (manual mode if needed) to maintain airflow and prevent high exhaust temperatures during cut-off periods.
• Maintain fuel oil injection viscosity between 12–13 cSt for correct atomization.
• Incorporate extra soot-blowing routines when using fuels prone to high carbon deposition.