Boiler Circulating Water Pump Failures

BCW FailureProject Unit Failure date Status of unit while

failureReason for failure

Dadri 5C 14-12-09 After Synchronization

Boiler water entry in pump

Simhadri 3C 29-05-11 After Synchronization

Large amount of iron powder in pump

Durgapur Andal

1B 27-07-11 During Commissioning

Boiler water entry in Pump

Vallur 1 A1B

30-08-11 During trial run of pump

Forced assy leading to impeller breakage

Jajjar After commissioning

Purge water Flange leakage

North chennai 1A During Erection

North chennai During Storage Preservative gas expired

BCW PUMP • Boiler circulating water pumps are provided for

forced circulation of water in water walls of 500 MW size and above.

• BHEL boilers are operating since 1985 with BCW pump.

• BCW pump imported from Hayward Tyler UK, KSB Germany and Torishima Japan. V-FLO China trial order has been placed.

• The pump and motor have glandless connection.

BCW PUMP problems

• The pump motor cavity is filled with cold water which is kept cool by circulating through a cooler. Boiler water which is at 340-360 °C at full load should not enter the pump. If it enters the pump motor cavity the motor will be damaged

• Boiler water can enter pump motor cavity only if the water in pump cavity is drained/leaking out.

• Motor chamber contains stator windings and rotor. The trip temperature is 66 °C.

Pump internals

Pump with cooler arrangement

BCW pump P & ID

Dadri unit 5

Dadri BCW PUMP Stator winding

Dadri Failure Analysis

• Damage due to hot boiler water entry into pump motor cavity

Simhadri unit 3

Simhadri

Pump casing drain

Simhadri failure analysis

• Simhadri Pump trial was conducted in Nov 2010. After that the unit has not been running on regular basis

• Boiler and pre boiler Corrosion material has entered the pump.

• The failure could have been avoided If the quality of water in pump was checked before taking it in to service.

• Drain line in pump casing was choked with similar material

Vallur- PUMP-A

VALLUR - PUMP A

VALLUR PUMP-B IMPELLER DAMAGE

VALLUR FAILURE ANALYSISPUMPS A&B

• From the Photographs it is clear that pump was forced in to the pump casing resulting in breakage of impeller. Foreign material was also in pump.

• Failure could have been avoided by proper care during installation

Durgapur failure

Durgapur failure

• The pump cavity temperature has increased about 150° C.

• Megger value of motor has come down.• Hot water has entered the motor.

ACTION TO BE TAKEN TO AVOID BCW PUMP FAILURE IN FUTURE

• BCW pump erection and commissioning should be done under the guidance of supplier representative.

• Drain valve handle to be removed to prevent accidental opening of drain.

• BCW pump to be flushed as per procedure before taking into service after long shut down. Water quality to be checked before starting the pump after long S/D.

• Training to be given to all operators at site.

PUMP NORTH CHENNAI

• PUMP- A DURING ERECTION IT FAILED • ANOTHER PUMP DURING STORING

PRESERVATIVE GAS EXPIRED.

THANKS