Consequences
- Pressure inside the Furnace will Increase
- Drum Level will start fluctuating(Sub-Critical Units)
- Flame will become Unstable
- Running I.D. Fan Motor current will increase
Possible Causes
- Electrical System Failure (Fault in the HT Motor/Supply Failure in the Bus/High Winding Temperature)
- Lube Oil System Failure (Lube Oil Pump Failure/ Lube Oil Pressure Low)
- Bearing Temperature High
- Failure of Cooling Water (**For Motor & Lube Oil)
- High Bearing Vibration
- Furnace Pressure Very High
- Furnace Pressure Very Low
- APH(Air Pre Heater) Tripped
Actions
- Put Furnace Pressure on Manual
- Decrease load on the running I.D.
- Cut the Mill & Take Oil Guns in Service for Flame Stability
- Adjust Load (MW) to boiler condition
- Stabilize Furnace draft by controlling the remaining fans(ID & FD) & Adjust the SADC(Secondary Air Damper Control) Dampers
- Stabilize Drum water level(Due to sudden load reduction, there is an increase in the drum level) by opening EBD(Emergency Blow Down)
- In case Steam Temperature plummets, watch Turbine differentials.
Local Operator Actions
- Check furnace flame condition.
- Check tripped fans for causes,
- Ready them for restart, inform control room.
**I.D. Fan – Induced Draft Fan
