Improving Efficiency

1

• Improving Efficiency Reliability
• of
• 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 ONgt
REDUCTION IN GENERATION COST ? HIGH
EFFICIENCY OF TG CYCLE ? LOWER
EQUIPMENT COST ? SHORTER GESTATION
PERIOD ? REDUCED MAINTENANCE TIME gt
INCREASED RELIABILITY gt 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..

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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
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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.
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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

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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
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PROPOSED NEW DESIGN WITH LATEST STATE OF ART
BLADING
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HP TURBINE

• EXISTING
• 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

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• 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

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• ACTIVITIES INVOLVED

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

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A. Reference data for ORIGINAL brand new
turbine Reference Heat Balance Diagram TCD -
210 - 33 - 2, Regime No. 1 Rated
parameters Main steam Flow 662
T/h Main Steam Pressure 130 ata Main
Steam Temperature 535 Deg C Hot reheat
Temperature 535 Deg C Condenser Vacuum
0.1042 ata TG Heatrate
2062 kCal/kWh
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• 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 202.4 MW
• Expected TG Heatrate
• with 662 T/h main steam flow
• and rated parameters 2164 kCal/kWh

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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)

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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
55.04 MU ADDITIONAL GEN. OF REVENUE _at_ RS 2/
PER UNIT 55.04 X 2 RS 11 CR
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Retrofit of LP TURBINE
200/210 MW IMPULSE DESIGN SET (LMW)
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EXISTING
AFTER RETROFIT
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• 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.

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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.

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A. Reference data for ORIGINAL brand new
turbine Reference Heat Balance Diagram TCD -
210 - 33 - 2, Regime No. 1 Rated
parameters Main steam Flow 662
T/h Main Steam Pressure 130 ata Main
Steam Temperature 535 Deg C Hot reheat
Temperature 535 Deg C Condenser Vacuum
0.1042 ata TG Heatrate
2062 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 202.4 MW
• Expected TG Heatrate
• with 662 T/h main steam flow
• and rated parameters 2164 kCal/kWh

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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)

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COMPARISON
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COMPARISON
GAIN WITH UPRATED LPT ADDITIONAL GEN. OF MU
MW X1000 X HRS.X PLF 10.1 X 1000 X 8000 X 0.80
64.64 MU ADDITIONAL GEN. OF REVENUE _at_ RS 2/
PER UNIT 64.64 X 2 RS 12.93 CR
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COMPARISON
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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 74.74 MU ADDITIONAL GEN. OF REVENUE _at_ RS
2/ PER UNIT 74.74 X 2 RS 14.848 CR
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TECHNICAL PROPOSAL
FOR R M OF 210 MW STEAM TURBINES (KWU DESIGN)
OF TUTICORIN TPS
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CROSS SECTIONAL VIEW OF 210 MW STEAM TURBINE
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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.

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210 MW STEAM TURBINE (REACTION DESIGN
SET-KWU)
HP TURBINE
RETROFITTING 210 MW REACTION TURBINE WITH
IMPROVED BLADING
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HP INLET INSERTS
HP OUTER CASING
BREECH NUT
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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
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IMPROVEMENTS IN PROPOSED DESIGN

• HP MODULE
• INNER CASING HP ROTOR WITH OPTIMISED HIGHLY
  EFFICIENT T4 PROFILE BLADING.
• ADVANTAGE
• INCREASED EFFICIENCY

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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.
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IMPROVEMENTS IN PROPOSED DESIGN (CONTD.)
HP MODULE (CONTD.) MODIFIED HP EXHAUST ELBOWS
WHICH HAVE U-RING IN PLACE OF SERRATED GASKET.
ADVANTAGE ENHANCED RELIABILITY.
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HP EXHAUST ELBOWS
Exhaust Elbow
HP OUTER CASING
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HP EXHAUST ELBOWS
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HP EXHAUST ELBOWS
U-RING
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SCOPE OF SUPPLY

• FOR HP TURBINE
• COMPLETELY ASSEMBLED HP MODULE WITH T4 PROFILE
  BLADING ALONGWITH MODIFIED HP INLET ASSEMBLY HP
  EXHAUST ELBOWS.

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

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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

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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.

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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.

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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.

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WORK REQUIRED TO BE DONE AT SITEFOR 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.

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CONDITION AFTER R M OF HPT IPT (UNDER RATED
CONDITION)

• RATED PARAMETERS
• At 100 MCR condition
• MAIN STEAM FLOW 641.3 T/HR
• MS/ HRH STEAM TEMP535/535 DEG C
• MAIN STEAM PR 150 ATA
• BACK PR 0.121 ATA

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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
641.3 T/HR MAIN STEAM FLOW AND RATED PARAMETERS
OUTPUT 202.3 MW HEAT RATE 2067 KCAL/KWH
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COMPARISON OF PERFORMANCE
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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 20.06 CRORES
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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 8.576 CRORES PER YEAR
• HENCE, PAY BACK PERIOD lt 3 YEARS

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Thank you
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PRESENT EXPECTED CONDITION OUT PUT 202.3 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.
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EXPECTED CONDITION AFTER RM OUT PUT 209 MW
(641.3T/HR) THEREFORE, OUT PUT 216.95 MW (665.7
T/HR) FOR THIS FLOW IT WILL BE OPERATING NEAR
VWO CONDITION WHICH IS NOT DESIRABLE.