What causes the fan bearing to vibrate during boiler operation?

Question details (Performance):

• 1. High temperature of motor, fast temperature rise.
• 2. Overload, high outlet pressure and frequent safety valve open often.
• 3. The vibration is intensified, the side vibration of the fan motor coupling is large, and the fan body never vibrates to vibration.
• 4. No obvious vibration was found in no-load test of fan motor.

Answer: Fault reason:

Fan bearing vibration is common fault in the operation, the vibration of the fan will cause damage of bearing and blade, bolt looseness, chassis and wind damage, fan vibration rises abruptly in the operation. this is because when the gas enter impeller and the rotating blade working face has certain angle, according to the principle of fluid mechanics, gas from non-working face must be a spiral blade, so the dust particles in the gas will slowly sedimentation due to vortex. Airfoil blades are very easy to accumulate dust.

When the accumulated ash reaches a certain weight, a part of the large amount of accumulated ash will be thrown out of the impeller due to the action of centrifugal force of the rotating impeller. Since the accumulation of ash on each blade cannot be completely uniform, the time of aggregation or swash may not be same.As a result, the impeller mass distribution is unbalanced due to the uneven accumulation of ash in the blade, which increases the fan vibration.

Troubleshooting:

1. If fan vibration, impact or friction are not as to cause equipment damage, fan load can be properly reduced, then make it continue to run, and to find out the cause of the problem and check the operation condition of the fan and eliminate as soon as possible, after treatment, if fan fault has not been cleared and continued to rise, then immediately stop the fan running.

2. Remove the accumulated dust on the blade, and the impeller will be balanced again, so as to reduce the vibration of the fan.