1. Improving Efficiency & Reliabilityof
STEAM TURBINE
Through R & M
BY:
AMITABH SRIVASTAVA
SR.DGM, BHEL HARDWAR

2. IN THE PRESENT POWER SECTOR SCENARIO
FOCUS IS ON
ENHANCING EFFICIENCY
RELIABILITY
STRICTER POLLUTION NORMS
COST REDUCTION

3. RESULTING TO ENHANCED EMPHASIS ON => REDUCTION IN GENERATION COST  HIGH EFFICIENCY OF TG CYCLE  LOWER EQUIPMENT COST  SHORTER GESTATION PERIOD  REDUCED MAINTENANCE TIME => INCREASED RELIABILITY => MINIMIZING ENVIRONMENTAL HAZARDS

4. IMPROVEMENT IN STEAM TURBINE PERFORMANCE
POSSIBLE BY
1. IMPROVED BLADE PROFILE
REDUCTION IN THE AERODYNAMIC
FLOW LOSSES e.g.
PROFILE LOSS
SECONDARY FLOW LOSS
TIP LEAKAGE LOSS
MORE UNIFORM FLOW DISTRIBUTION
CONTD……..

5. IMPROVEMENT IN STEAM TURBINE PERFORMANCE
POSSIBLE BY ….contd...
2. OPTIMISED FLOWPATH
3. IMPROVEMENT IN SHAFT SEALING SYSTEM
4. REDUCTION IN PRESSURE DROPS
5. REDUCED FRICTION LOSSES
6. OPTIMISATION OF INLET & EXHAUST SECTION
7. OPTIMISED EXHAUST LOSS

6. DEVELOPMENT OF PROFILES FOR CYLINDRICAL TURBINE BLADES
T4 PROFILE HAS 1% LOWER PROFILE LOSSES COMPARED TO T2 PROFILE.
NEWLY DEVELOPED TX HAS 0.2% LOWER PROFILE LOSSES COMPARED TO T4 PROFILE.

7. CONSIDERATIONS IN RETROFITTING & UPGRADATION OF OLDER SETS
COST EFFECTIVENESS
MODIFICATIONS IN TURBINE INTERNALS
ONLY
INCREASE IN POWER OUTPUT WITH MINIMUM
CHANGES
OUTER CASING, PIPINGS, VALVES, PEDESTAL
FIXING ARRANGEMENT , STEAM PARAMETERS
& FOUNDATION DETAILS REMAIN UNALTERED
SHORTEST POSSIBLE OUTAGE TIME

8. RETROFITTING & UPGRADATION OF OLDER SETS
PRE-REQUISITE
IDENTIFY THE UNIT
PRESENT LEVEL OF PERFORMANCE
RESIDUAL LIFE ASSESSMENT STUDY OF CRITICAL COMPONENTS
ANALYSIS OF HISTORY & OPERATING DETAILS

9. RETROFITTING & UPGRADATION OF OLDER SETS
MAJOR MODIFICATIONS IN
GUIDE & MOVING BLADE
(LATEST STATE OF ART PROFILE)
STEAM FLOWPATH
ROTORS & INNER CASINGS OF TURBINE
SHAFT SEALINGS
[ADVANTAGE IN HEATRATE / OUTPUT CAN BE WORKED OUT ON CASE TO CASE BASIS]
3 DS BLADE
(HPT/IPT)
TWISTED PROFILE
BLADE (HP/IPT)
BANANA TYPE
BLADE (LPT)

10. Retrofitting of HP Turbine with STATE OF ART REACTION BLADING

11. (IMPULSE DESIGN SET-LMW)
210 MW STEAM TURBINE
(IMPULSE DESIGN SET-LMW)
HP TURBINE

12. 210 MW STEAM TURBINE (IMPULSE DESIGN SET)
HP TURBINE
EXISTING 210 MW HP TURBINE WITH IMPULSE BLADING
PROPOSED NEW DESIGN WITH LATEST STATE OF ART BLADING

13. PROPOSED NEW DESIGN WITH LATEST STATE OF ART BLADING

14. HP TURBINE EXISTING NEW IMPULSE BLADING
( PRESSURE DROP ONLY IN STATIONARY BLADES)
EFFICIENCY : 83.6 %
(FOR NEW MACHINE)
EFFICIENCY FOR EXISTING CONDITION : ~ 80%
NEW
REACTION BLADING ( PRESSURE DROP IN STATIONARY AS WELL AS MOVING BLADES
EFFICIENCY : 86.5 %

15. ACTIVITIES INVOLVED
REMOVAL OF EXISTING HP ROTOR, LINERS AND DIAPHRAGMS
INSTALLATION OF NEW LINERS FITTED WITH STATIONARY BLADES AND NEW HP ROTOR
FITTING DIMENSIONS ARE TO BE MEASURED DURING PREVIOUS OVERHAUL AND LINERS ARE MACHINED ACCORDINGLY.
REMOVED HP ROTOR AND DIAPHRAGMS CAN BE USED AS SPARE FOR OTHER SETS

16. ACTIVITIES INVOLVED
THE RETROFIT CAN BE DONE WITHIN NORMAL OVERHAUL PERIOD.
PAY BACK PERIOD IS LESS THAN 3 YEARS

17. A. Reference data for ORIGINAL brand new turbine
Reference Heat Balance Diagram
TCD , Regime No. 1
Rated parameters
Main steam Flow T/h
Main Steam Pressure ata
Main Steam Temperature Deg C
Hot reheat Temperature Deg C
Condenser Vacuum ata
TG Heatrate kCal/kWh

18. B. Expected present performance level (210 MW Original rating)
Considering deterioration due to ageing as per ASME-PTC-6Report 1985
Expected Power output
with 662 T/h main steam flow
and rated parameters MW
Expected TG Heatrate
and rated parameters kCal/kWh

19. INCREASE IN POWER OUTPUT : 8.6 MW IMPROVEMENT IN HEATRATE : 4%
EXPECTED PERFORMANCE IMPROVEMENT IN THE EXISTING IMPULSE DESIGN SET DUE TO HP TURBINE REFURBISHMENT
INCREASE IN POWER OUTPUT : 8.6 MW
IMPROVEMENT IN HEATRATE : 4%
(FROM EXISTING PERFORMANCE LEVEL OF THE SET WITH RATED STEAM PARAMETERS & THROTTLE STEAM FLOW)

20. EXPECTED PERFORMANCE IMPROVEMENT IN THE EXISTING IMPULSE DESIGN SET DUE TO HP TURBINE REFURBISHMENT

21. COMPARISON GAIN WITH UPRATED HPT:
ADDITIONAL GEN. OF MU = MW X1000 X HRS.X PLF
= 8.6 X 1000 X 8000 X 0.80 = MU
ADDITIONAL GEN. OF RS 2/= PER UNIT
= X 2 = RS 11 CR

22. Retrofit of LP TURBINE
200/210 MW IMPULSE DESIGN SET
(LMW)

23. EXISTING
AFTER RETROFIT

26. WORK INVOLVED IN RETROFIT OF LP TURBINE
WORK TO BE DONE AT SITE:
CUTTING OF DEFLECTORS / RIBS & BLANKING THE SPACE IN LP CASING TO FACILITATE REMOVAL OF BAUMEN STAGE.
MODIFICATION OF STRUCTURE AT THE EXHAUST END OF LPC TO FACILITATE INSTALLATION OF DIFFUSOR.
CONTD….

27. WORK INVOLVED IN RETROFIT OF LP TURBINE
WORK TO BE DONE AT SITE:
MODIFICATION OF STRUCTURE AT THE STEAM INLET END OF LPC TO FACILITATE INSTALLATION OF 1ST STAGE OF GUIDE BLADES.

28. A. Reference data for ORIGINAL brand new turbine
Reference Heat Balance Diagram
TCD , Regime No. 1
Rated parameters
Main steam Flow T/h
Main Steam Pressure ata
Main Steam Temperature Deg C
Hot reheat Temperature Deg C
Condenser Vacuum ata
TG Heatrate kCal/kWh

29. B. Expected present performance level (210 MW Original rating)
Considering deterioration due to ageing as per ASME-PTC-6Report 1985
Expected Power output
with 662 T/h main steam flow
and rated parameters MW
Expected TG Heatrate
and rated parameters kCal/kWh

30. INCREASE IN POWER OUTPUT : 10.1 MW
EXPECTED PERFORMANCE IMPROVEMENT IN THE EXISTING SET DUE TO LP TURBINE REFURBISHMENT
INCREASE IN POWER OUTPUT : 10.1 MW
IMPROVEMENT IN HEATRATE : 102 KCAL / KWH
(FROM EXISTING PERFORMANCE LEVEL OF THE SET WITH RATED STEAM PARAMETERS & THROTTLE STEAM FLOW)

31. COMPARISON

32. COMPARISON GAIN WITH UPRATED LPT:
ADDITIONAL GEN. OF MU = MW X1000 X HRS.X PLF
= 10.1 X 1000 X 8000 X 0.80 = MU
ADDITIONAL GEN. OF RS 2/= PER UNIT
= X 2 = RS CR

33. COMPARISON

34. COMPARISON GAIN WITH UPRATED HPT & LPT:
ADDITIONAL GEN. OF MU = MW X1000 X HRS.X PLF
= 11.6 X 1000 X 8000 X 0.80 = MU
ADDITIONAL GEN. OF RS 2/= PER UNIT
= X 2 = RS CR

35. FOR R & M OF 210 MW STEAM TURBINES (KWU DESIGN) OF TUTICORIN TPS
TECHNICAL PROPOSAL
FOR R & M OF 210 MW STEAM TURBINES (KWU DESIGN) OF TUTICORIN TPS

36. CROSS SECTIONAL VIEW OF 210 MW STEAM TURBINE

37. EXISTING DESIGN: HP Turbine:
HP ROTOR : WITH MOVING BLADES OF T2 PROFILE
INNER CASING: WITH STATIONARY BLADES OF
T2 PROFILE
INLET INSERTS: WITH 580X9 MM BUTTRESS
THREADS
EXHAUST ELBOWS: WITH SERRATED GASKET.

38. (REACTION DESIGN SET-KWU)
210 MW STEAM TURBINE
(REACTION DESIGN SET-KWU)
HP TURBINE
RETROFITTING 210 MW REACTION TURBINE WITH IMPROVED BLADING

39. HP INLET INSERTS
HP OUTER CASING
BREECH NUT

40. HP INLET INSERTS HP INLET INSERTS (OLD DESIGN):
HP OUTER CASING & BREECH NUTS THREAD SIZE : 580X9 MM
HP INLET INSERTS (NEW DESIGN):
HP OUTER CASING & BREECH NUTS
THREAD SIZE : 580X20 MM

41. IMPROVEMENTS IN PROPOSED DESIGN:
HP MODULE:
INNER CASING & HP ROTOR WITH OPTIMISED HIGHLY EFFICIENT T4 PROFILE BLADING.
ADVANTAGE:
INCREASED EFFICIENCY

42. IMPROVEMENTS IN PROPOSED DESIGN: (CONTD.)
HP MODULE (CONTD.):
MODIFIED HPT INLET INSERTS WITH BUTTRESS THREADS OF SIZE 580X20 MM IN HP OUTER CASING & BREECH NUTS.
ADVANTAGE:
EASE IN ASSEMBLY & DISMANTLING.

43. IMPROVEMENTS IN PROPOSED DESIGN: (CONTD.)
HP MODULE (CONTD.):
MODIFIED HP EXHAUST ELBOWS WHICH HAVE U-RING IN PLACE OF SERRATED GASKET.
ADVANTAGE:
ENHANCED RELIABILITY.

44. HP EXHAUST ELBOWS
Exhaust Elbow
HP OUTER CASING

45. HP EXHAUST ELBOWS

46. HP EXHAUST ELBOWS
U-RING

47. SCOPE OF SUPPLY FOR HP TURBINE:
COMPLETELY ASSEMBLED HP MODULE WITH T4 PROFILE BLADING ALONGWITH MODIFIED HP INLET ASSEMBLY & HP EXHAUST ELBOWS.

48. 210 MW STEAM TURBINE (REACTION DESIGN SET-KWU)
IP TURBINE
RETROFITTING 210 MW REACTION TURBINE WITH IMPROVED T4 PROFILE BLADING
ADVANTAGE:
IMPROVED PERFORMANCE.

49. SCOPE OF SUPPLY (CONTD.)
FOR IP TURBINE:
IP INNER CASING & IP ROTOR WITH T4 PROFILE BLADING.
A SET OF HPR-IPR & IPR-LPR COUPLING BOLTS.
NECESSARY KEYS ETC.

50. WORK REQUIRED TO BE DONE AT SITE:
[NOT INCLUDED IN THE SCOPE OF THIS TECHNICAL OFFER]
PERFORMANCE TESTING PRIOR & AFTER R & M.
OVERHAULING.
RLA STUDY.
COMPONENTS IDENTIFIED DURING OVERHAULING/ RLA STUDY WHICH NEED REPLACEMENT

51. WORK REQUIRED TO BE DONE AT SITE: (FOR HP Turbine)
REMOVAL OF OLD HP MODULE FROM ITS POSITION AFTER DISMANTLING OF HP INLET INSERTS AND HP EXHAUST ELBOWS.
OLD HP INLET ASSEMBLY (INLET INSERTS WITH BREECH NUTS) & HP EXHAUST ELBOWS ARE TO BE CUT FROM MS PIPES & CRH PIPES RESPECTIVELY.

52. WORK REQUIRED TO BE DONE AT SITE:(CONTD.)
INSTALLATION OF NEW IMPROVISED HPT MODULE IN POSITION, CENTERING & ALIGNMENT.
WELDING OF HP INLET ASSEMBLY OF NEW MODULE WITH MAIN STEAM PIPES.

53. WORK REQUIRED TO BE DONE AT SITE:(CONTD.)
HP EXHAUST ELBOWS ARE TO BE WELDED WITH CRH STEAM PIPES.
ASSEMBLY OF HP INLET INSERTS & HP EXHAUST ELBOWS TO BE COMPLETED.

54. WORK REQUIRED TO BE DONE AT SITE:FOR IP Turbine
REMOVAL OF OLD IP ROTOR & IP INNER CASING.
INSTALLATION OF NEW IP INNER CASING & IP ROTOR WITH T4 PROFILE BLADING, ITS CENTERING & ALIGNMENT.
COMPLETION OF BOX UP OF IP Turbine.

55. CONDITION AFTER R & M OF HPT & IPT (UNDER RATED CONDITION):
RATED PARAMETERS:
At 100% MCR condition
MAIN STEAM FLOW : T/HR
MS/ HRH STEAM TEMP:535/535 DEG C
MAIN STEAM PR: 150 ATA
BACK PR: ATA

56. EXPECTED PRESENT PERFORMANCE:
CONSIDERING DETERIORATION DUE TO AGING AS PER ASME-PTC-6 REPORT 1985 FOR AVERAGE LIFE OF 20 YEARS, FOLLOWING WILL BE EXPECTED PERFORMANCE AT T/HR MAIN STEAM FLOW AND RATED PARAMETERS
OUTPUT: MW
HEAT RATE: 2067 KCAL/KWH

57. COMPARISON OF PERFORMANCE:

58. PAY BACK PERIOD 1) REDUCTION IN OH PERIOD: 25 DAYS
RESULTING TO
ADDITIONAL POWER GENERATION FOR 25 DAYS
YIELDING TO
GUAREENTED MINIMUM ADDITIONAL REVENUE:
= 209MW x 1000 x 25DAYS x 24HRS x 0.80PLF x 2.00RS
=RS CRORES

59. PAY BACK PERIOD
ADDITIONAL ANNUAL REVENUE GENERATION DUE TO INCREASE IN OUTPUT & IMPROVED HEAT RATE:
= 6.7 MW x 1000 x 8000 HRS x 0.80 PLF x RS 2.00
= RS CRORES PER YEAR
HENCE, PAY BACK PERIOD < 3 YEARS

60. Thank you

61. PRESENT EXPECTED CONDITION:
OUT PUT = MW (641.3T/HR)
THEREFORE,
OUT PUT = 210 MW (665.7 T/HR)
FOR THIS FLOW : IT IS OPERATING NEAR TO VWO CONDITION WHICH IS NOT DESIRABLE.

62. EXPECTED CONDITION AFTER R&M:
OUT PUT = 209 MW (641.3T/HR)
THEREFORE,
OUT PUT = MW (665.7 T/HR)
FOR THIS FLOW : IT WILL BE OPERATING NEAR VWO CONDITION WHICH IS NOT DESIRABLE.