Emergencies handling in Unit 5

Anoop Kumar SharmaOpn G-D103162EventsTD BFP A tripping on 27/06/2013(15.48)TD BFP A tripping on 27/06/2013(18.24)MD BFP C discharge v/v closed on 24/07/2013(15.15)Approach, Learning's!Unit Tripping- What it means ?Queries?Presentation OutlineTD BFP A tripping on 27/06/2013(15.48)TD BFP A tripping on 27/06/2013(18.24)MD BFP C discharge v/v closed on 24/07/2013(15.15)EventsShift In charge- Sh. T N YadavUnit Controller- Sh. Rakesh Anand.Er. Naveen KumarEr. Anoop Kr. SharmaEr. Saroj Kr. YadavaEr. Sandeep Kr. MalikRahul Kumar(DT)Jatinder Singh(DT)TeamUnit Condition before tripping (15:47)

7 Mills in Service A,B,C,D,G,H,JUnit Load 502 MWThrottle Pressure 168.7 Coal flow 310 TDrum level -10

TD BFP A tripping on 27/06/2013(15.48)

At 15. 48 TD BFP A tripped, Alarm came in BHEL ,no sound was there.

TD BFP A tripping on 27/06/2013(15.48)Reason

De aerator level transmitter root v/v left side was isolated by TMD worker.Resulting in D/A lvl V. low tripping in TD BFP.

TD BFP A tripping on 27/06/2013(15.48)SchemeDE AERATOR1243Root v/vRoot v/vLevel GaugeD/A lvl V. Low tripping 2 out of 31,2,3 -TD BFP A,B2,3,4-MD BFP CActions

In Boiler side Feeder J was cut at 15.49.20, Mill G at 15.49.50was cut immediately.Load was decreased immediately to 350 MW by Pr max. final limiter.Subsequently feeder H was cut and Mill H,J were cut.MD BFP was in auto.

TD BFP A tripping on 27/06/2013(15.48)

Pr. MaxMill G CutActual LoadMill J CutMill H CutFeeder J cut

LoadDrum LevelCoal FlowMD BFP C scoop struck at 73, was taken in manual and flow raised to 1000 T.

Drum level was maintained within trip limits.Roadblocks & HandlingFunctionMinimumMaximumLoad270 @15.59499 @15.47Drum Level-328 @15.50129 @16.02Coal151 @ 15.51310 @15.47Unit Condition before tripping (18:23)

7 Mills in Service A,B,C,D,E,H,JUnit Load 505 MWThrottle Pressure 170.7 Coal flow 318 TDrum level +15

TD BFP A tripping on 27/06/2013(18.24)

At 18. 24 TD BFP A tripped, Alarm came in BHEL.TD BFP A tripping on 27/06/2013(18.24)Reason

TD RJ Bearing Vibration shoot up to 149 for 5sResulting in TD BFP A tripping at RJB vibration V high.

Alarm value at 50 mm/secTrip value at 70 mm/sec for 5 sec.Now changed to 30 sec.

TD BFP A tripping on 27/06/2013(18.24)Actions

In Boiler side Mill J was cut at 18.26, Mill H at 15.26.50 was also cut immediately.Load was decreased immediately to 350 MW by Pr max. final limiter.Subsequently Mill E was cut.MD BFP was in Auto.

TD BFP A tripping on 27/06/2013(18.24)

Pr. MaxMill H,J CutActual LoadMill E CutThrottle Pr.

LoadDrum LevelCoal FlowMD BFP C was taken in manual to manage drum level.Drum level was maintained within trip limits.Pr Max. was reduced to 300 MW resulting in increase in Throttle Pressure by 178 so By pass opened , load should be taken, feeding in top mill should be decreased.

Roadblocks & HandlingFunctionMinimumMaximumLoad251 @18.26492 @18.24Drum Level-326 @18.26191 @18.34Coal152 @ 18.24318 @18.31Unit Condition before tripping (15:14)

7 Mills in Service A,B,C,D,F,G,HUnit Load 498 MWThrottle Pressure 171.2Coal flow 312 TDrum level -5

MD BFP C Discharge v/v closed on 24/07/2013(15.15)

Observations

Drum level started decreasing as MDBFP recirculation opened.We tried to close re circulation, but it was not getting closed. 550-600 T flow was shown in screen so scoop was increased.Mean while it was seen that discharge pressure was 0 kg and discharge valve was in closed condition.

MD BFP C Discharge v/v closed on 24/07/2013(15.15)

Actions:

Immediately scoop was reduced to 0 and in some time discharge valve was opened from local.Mill F,G,H were cut.Load was reduced by Pr. Max to 350 MW.

MD BFP C Discharge v/v closed on 24/07/2013(15.15)

Mill F,G,H CutActual LoadThrottle Pr.

LoadDrum LevelCoal FlowTD BFP A came in manual ,ACV opened , speed reduction took time.High reduction in coal flow so load reduced to 220 hence drum level shoot up , 1st roadblock added to it.1 person was sent in local to open discharge v/v and then scoop was increased along with feedingRoadblocks & HandlingFunctionMinimumMaximumLoad219 @15.33498 @15.16Drum Level-354 @15.22349 @15.27Coal145 @ 15.25311 @15.19Approach, learning's !Cut 2 Mills ImmediatelyAfter some time delay (30s) cut 3rd MillDecrease Load to 350 by Pr. MaxFurther reduction to 300 MW watching throttle Pr. If by pass opens take load, decrease feeding in top millIn MD Tripping Manage TD with large commands for good responseSAVING UNIT, HANDLING EMERGENCY500 MW for 1 hr.500*1000=0.5 *10^60.5MU lost in 1 hour.Taking 1 unit cost Rs. 1 (NTPCs avg. 2.50)0.5 million rupee.For 4 hours 2 million rupeesAdding cost due to loss of schedule and oil etc.Approx. 25 lacUnit Tripping-What it Means?

QUERIES ?