Case Study on Bfp Mod.

NTPC LTD, RAMAGUNDAMNTPC LTD, RAMAGUNDAM

TDBFP TDBFP FAILUREFAILURE

A case studyA case study


TDBFP AN OVER VIEWTDBFP AN OVER VIEW PUMP IS DRIVEN BY TURBINE OF 14 STAGES.

TURBINE IS DIRECTLY CONNECTED WITH MAIN MAIN PUMP BY HYDRAULIC COUPLING UNIT AND TO THE BOOSTER PUMP THROUGH GEAR BOX

MAIN PUMP CONSISTS OF 4+1 (KICKER) STAGE.

TURBINE IS HAVING 5 Nos OF CONTROL VALVE WITH ONE STOP VALVE AND ONE ACV.

3 STEAM SOURCES TO DRIVE THE TURBINE CRH STEAM AUXILARY STEAM IP-LP CROSS OVER STEAM

NTPC LTD, RAMAGUNDAM

TDBFP AN OVER VIEW

FR

OM

D/A

FR

OM

D/A

AUX STEAMAUX STEAM

CRHCRH

SH SPRAYSH SPRAY

TO CONDENSORTO CONDENSOR

RH SPRAYRH SPRAY

LP-IP CROSS OVERLP-IP CROSS OVER

TO

FR

ST

O F

RS

GBGB

COUPLINGCOUPLING

MAINMAINPUMPPUMP TURBINETURBINE

BOOSTERBOOSTERPUMPPUMP

HCHC


UNIT : 5

DATE : 09/03/2006 22:41:30 HRS

LOAD : 490 MW

MILLS IN SERVICE : A B C D E F

BFPs IN SERVICE : - TDBFP A ON EXTRACTION - TDBFP B ON EXTRACTION WITH CRH LINED UP. - ( MDBFP AUTO STANDBY )

UNIT STATUS BEFORE EMERGENCYUNIT STATUS BEFORE EMERGENCY::

CASE STUDY


1. ACV CHANGE OVER ALARM APPEARED.

2. BFP-A GOT UNLOADED.

3. FEED WATER FLOW DROPPED BY 400 T/HR.

4. BFP –A SPEED INCREASED FROM 5387 RPM TO 5923 RPM AND MAINTAINED AT 5728 RPM.

OBSERVATIONS:OBSERVATIONS:


5. TURBINE FRONT VIBRATION INCREASED FROM 44µ TO 53 µ.

6. TURBINE ECCENTRICITY INCREASED FROM 32µ TO 39µ.

7. GEAR BOX FRONT VIBRATION INCREASED FROM 8 µ TO 25 µ

8. CV POSITION REDUCED FROM 41 TO 28 %.

OBSERVATIONS (conti:):OBSERVATIONS (conti:):


1. MDBFP STARTED MANUALLY, LOADED AND DRUM LEVEL NORMALISED.

2.MEANWHILE BFP –A R/C VALVE OPENED MANUALLY AS R/C VALVE DIDN’T OPEN IN AUTO ON LOW FLOW.

3. IN LOCAL BFP-A TURBINE TO GEAR BOX COUPLING FOUND IN DECOUPLED CONDITION AND SPARK WAS COMING,IMMEDIATELY BFP-A HAND TRIPPED.

ACTIONS TAKEN :ACTIONS TAKEN :


BFP-A SPEED CAME DOWN TO ZERO AND AGAIN STARTED ROTATING AT A SPEED OF 3360 RPM.

SH SPRAY BECAME ZERO AND WAS NOT INCREASING SH SPRAY BECAME ZERO AND WAS NOT INCREASING WITH ALL VALVES IN FULL OPEN CONDITION.WITH ALL VALVES IN FULL OPEN CONDITION.

DUE TO NON AVAILIBILITY OF SH SPRAY, STEAM DUE TO NON AVAILIBILITY OF SH SPRAY, STEAM TEMPERATURE AND METAL TEMPERATURE STARTED TEMPERATURE AND METAL TEMPERATURE STARTED RAISING.RAISING.

MS TEMPERATURE WENT UPTO 560°C , SH / RH METAL TEMPERATURE HAS GONE UPTO 600°C.


TDBFP HAND TRIPPEDTDBFP HAND TRIPPED

Speed dropped to 20 rpmSpeed dropped to 20 rpm


4. FIRST MILL- F AND LATER MILL- E HAND TRIPPED BUTSTILL TEMPERATURE WAS INCREASING HENCE LOAD BROUGHT DOWN TO 230 MW.

5. SINCE BFP-A SPEED WAS NOT REDUCING, SUSPECTED BFP REVERSE ROTATION DUE TO PROBLEM WITH SH SPRAY LINE NRV OF BFP.

Actions taken (conti: )Actions taken (conti: )


6. BFP-A SH SPRAY MANUAL ISOLATING

VALVE CLOSED.

7. WITH THIS SH SPRAY STARTED

INCREASING AND BFP–A SPEED CAME

DOWN TO ZERO.

8. HYD COUPLING BETWEEN MAIN PUMP

AND TURBINE DISENGAGED AND

TURBINE PUT ON BARRING GEAR.

Actions taken (conti: )Actions taken (conti: )


OTHER OBSERVATIONS:OTHER OBSERVATIONS:

WHILE CLOSING BFP-A SH SPRAY VALVE, WHILE CLOSING BFP-A SH SPRAY VALVE, BFP SPEED STARTED COMING DOWN AND BFP SPEED STARTED COMING DOWN AND SAME TIME ECC AND VIB GONE UP TOSAME TIME ECC AND VIB GONE UP TO

ECC - 262ECC - 262µµ VIB (F) - 131µ VIB ( R ) - 128µ GB ( F )- 35µ GB ( R )- 15µ AND IT HAS CAME BACK TO NORMAL AND IT HAS CAME BACK TO NORMAL VALUES AFTER PUTTING TURBINE ON VALUES AFTER PUTTING TURBINE ON BARRING.BARRING.

TURBINE HAS NOT COME TO BARRING DURING COASTING DOWN


MAIN CAUSESMAIN CAUSES

BFP COUPLING FAILUREBFP COUPLING FAILURE::

RESULTED IN UNLOADING OF TDBFP.RESULTED IN UNLOADING OF TDBFP.

SH SPRAY NRV FAILURESH SPRAY NRV FAILURE::

RESULTED IN 1. REVERSE ROTATION OF BFP.RESULTED IN 1. REVERSE ROTATION OF BFP.

2. STEAM AND METAL TEMP RISE.2. STEAM AND METAL TEMP RISE.

3. GENERATION LOSS.3. GENERATION LOSS.


BFP TURBINE TO BOOSTER PUMP COUPLINGBFP TURBINE TO BOOSTER PUMP COUPLING

POINT OF POINT OF FAILUREFAILURE


COUPLING CROSS SECTIONAL VIEWCOUPLING CROSS SECTIONAL VIEW

TURBINE

SIDE

GB

SIDE


BFP SH SPRAY NRV :

FROM BFPFROM BFPDISCHARGEDISCHARGE

FAILED NRV

TO SH SPRAYCOMMON HEADER


RECOMMENDATIONRECOMMENDATIONS:S:

1. FOR INDIVUDAL BFPs SH AND RH SPRAY MOTORISED VALVES TO BE PROVIDED IN ADDITION TO MANUAL ISOLATING VALVE.

2. IF BFP TRIPS, RESPECTIVE BFP’S SH AND RH SPRAY MOTORISED VALVES CLOSING INTER LOCK TO BE PROVIDED.

3. BFP FLOW LOW ALARM TO BE PROVIDED (LESS THAN 250 T /HR ).


THANK YOU

Case Study on Bfp Mod.

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