Normally the differential pressure between discharge and suction sides of
Boiler Feed Pumps are quite high. Due to this, the rotor section experiences
very high trust in one direction. The movement of rotor (Axial shift), if it
exceeds manufacturer's tolerances, will result in rubbing of mechanical seals
and damage the same. A Balance Drum is created by interconnecting suction and
discharge sides suitably and the wear out of seals can be inferred by measuring
Balance drum pressure.
Saturday, 7 December 2013
53.What are the trip commands for a pump?
Typical Trip interlocks for Pumps are: Bearing Temp OR Vibration High,Lube
oil press Low, Suction valve Closed , Electrical switch gear faults.
52. What are the trip commands for a Fan?
Typical Trip interlocks for fans are: Bearing Temp OR Vibration High,Lube
oil press Low, Electrical
switchgear faults.
51.What is partial loss of flame?
In a wall fired boiler when a flame
scanner sense no flame, the respective burner shut-off valves are demanded to
close. If they are failed to close after 10 sec. it is announced as Partial
Flame loss.
If the number burners are less than a
number which can cause unsafe condition, MFT will be initiated. Sometimes a
load factor less then 75% is also ANDed for MFT.
Conservatively some plants are initiating
MFT for Partial Flame loss irrespective of any condition of the boiler.
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