gland stem

NTPC/TSTPP OPERATION DEPARTMENT TS - II/OPN/OI /TG/ /10

AREA – TG Operating Instruction for Gland Steam Condenser Isolation and Normalisation

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UNIT - 3/4/5/6 Date: 04/10/2007

Sheet 1 Of 3

Prepared By Sri K.Ch. Satyanarayana,S(O)

Reviewed By Sri R.N.Das , SS(O)

Approved By Sri D.Sarkar , DGM(O)

A PURPOSE: -

This document is prepared to guide the operating personnel while isolating & normalizing the Gland Steam Condenser when unit in operation in stage- II units.

B SCOPE: -

This shall be applicable to all the 4 units of Stage – II (4X 500 MW units), TSTPP, NTPC Ltd.

C INTRODUCTION: - Gland steam condenser is provided in the condensate system between CEP discharge header

and deaerator level control valves to extract heat from the steam coming from the turbine glands . GSEB exhausts the non condensable gasses and some water vapour to the atmosphere. After cooling the steam, the drip from the GSC is connected either to LPDFT or to the atmosphere as per the operation requirement. Normally it is lined up to the LPDFT .To ensure minimum flow through the gland steam condenser, a minimum flow recirculation line with control valve is connected from the discharge header before deaerator level control block valve back to condenser. An emergency motorised valve MAW AA007 is provided in the upstream of the GSC steam inlet motorised valve MAW AA001 and connected to atmosphere as safety valve . Turbine gland seal leak off is normally connected to GSC but in case of emergency, it is connected to atmosphere through an emergency motorized valve MAW AA007 (safety valve) . Normal flow requirement through the GSC is around 400 T/Hr .

D TECHNICAL DATA OF THE SYSTEM Design pressure: -

Shell side: Full vacuum & 39 kg/ cm² (g) Tube side: 39 kg/ cm² (g)

Design temperature: Shell side: 300ºC Tube side: 100ºC

D RESPONSIBILITY:

UCE /SCE/ OPERATION SUPPORT GROUP

E ISOLATION PROCEDURE FOR GSC

E-1 PRECONDITION OF THE UNIT: -

1. Unit is running at full load (500MW). 2. Vacuum is maintaining normal i.e. - 0.90 kg/cm². 3. Seal steam pressure is maintaining normal i.e. 250 mmwc. 4. Seal steam header pressure controller in auto. 5. Any one Gland Seal Condenser Exhaust Blower in service and other is available. 6. Both ID, both FD and both PA fans in service. 7. Two CEPs are in service and third CEP is in standby mode. 8. GSC drip is connected to LPDFT and drip to atmosphere in closed condition.



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UNIT - 3/4/5/6 Date: 04/10/2007

Sheet 2 Of 3




E-2 STEAM SIDE ISOLATION: -

9. Close fully the drip line to LPDFT & along with the strainer bypass manual valve and then open drip line valve to atmosphere. Check the condenser vacuum for any drop.

10. Open the emergency motorised valve MAW AA007 (safety valve) provided in the upstream of the GSC steam inlet motorised valve MAW AA001 and connected it to atmosphere.

11. Close GSC steam inlet motorised valve MAW AA001. 12. Stop GSC exhaust fan 1 / 2 by pressing the EPB as they will not stop from remote and close suction

motorised valves MAWAA011 / MAWAA012.

E-3 CONDENSATE SIDE ISOLATION: -

13. Gradually open GSC condensate bypass manual valve CD17 to full open. Check CEP discharge header pressure while opening the bypass valve.

14. Gradually close GSC condensate inlet manual valve CD16. Check condensate flow to Deaerator and CEP discharge header pressure.

15. Gradually close GSC condensate outlet manual valve CD18. Check CEP header pressure. 16. Depressurise the GSC condensate (water box) side by opening manual vent valves. 17. Open the GSC condensate (water box) side manual drains to facilitate maintenance as per the

requirement.

F NORMALISATION PROCEDURE FOR GSC

F-1 CONDENSATE SIDE NORMALISATION: -

18. Check the PTW in the system is cancelled & necessary clearance given by Maint departments . 19. Open both the vents provided on water box (condensate) side. 20. Close both drains provided on water box (condensate) side. 21. Crack open GSC condensate inlet manual valve CD16. Check vents for proper venting and close after

completion of venting i.e. when pure water is coming out from the vents. 22. Gradually full open GSC condensate inlet manual valve CD16. 23. Gradually open GSC condensate outlet manual valve CD18. 24. Gradually fully close the GSC condensate bypass manual valve CD17. Check condensate flow to

Deaerator and CEP discharge header pressure.

F-2 STEAM SIDE NORMALISATION: -

25. Ensure the GSC overflow drain line siphon is filled , otherwise fill it through the filling line provided from the condensate line through the vents / drains .

26. Open GSEB 1 / 2 suction motorized valves MAWAA011 / MAWAA012 and start any one GSEB 1 / 2 by releasing the EPB .

27. Open GSC steam side inlet motorized valve MAW AA001. 28. Close emergency motorized valve MAW AA007 to atmosphere. 29. Observe the drip level and ensure water is coming from the drip line connected to atmosphere. 30. Gradually close drip line to atmosphere fully. After full closing, open the drip line valve to LPDFT. Keep

open / close strainer bypass valve as per the operation requirement. Observe for any vacuum drop.

$$ $$$ END $$ $$$



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UNIT - 3/4/5/6 Date: 04/10/2007

Sheet 3 Of 3




SCHEMATICS OF GSC

gland stem

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