ENERGY AUDIT AT R-INFRA DAHANU THERMAL POWER STATION (250 X 2 MW UNIT)

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ENERGY AUDIT AT R-INFRA DAHANUTHERMAL POWER
STATION (250 X 2 MW UNIT)

• CENTRAL POWER RESEARCH INSTITUTE, BANGALORE-560080

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MERC CONTRACT TO CPRI

• INVESTIGATION INTO PERFORMANCE OF DTPS R-INF
• PERIOD 2 MONTHS FROM 22.01.2010
• TOR RATING OF THE UNITS
• PERMISSIBLILITY OF MW OVERLOADING OF THE UNIT
  ABOVE THE MCR VALUE
• DE-RATING/UP-RATING OF THE UNITS
• FACT FINDING OF UNIT CAPACITY HISTORY
• TESTS ON UNITS CONSTRAINTS

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DESIGN CAPACITY/ RATING OF DTPS

• INSTALLED DURING BSES PERIOD 1995
• TAKEN OVER BY R-INFRA IN 2003
• NO MAJOR CHANGE IN HARDWARE SINCE
• IDENTICAL TO OVER 25 250 MW UNITS INSTALLED ALL
  OVER INDIA INCLUDING PARLI, PARAS TATA TROMBAY.
  
• SAME DESIGN REPLICATED IN ALL UNITS. THEY ARE OF
  STAND 250 MW DESIGN OF BHEL
• PG TEST, INSTALLATION MANUALS, NAME PLATES,
  CAPACITY TESTS OF EQUIPMENT AND C I INDICATE
  UNITS ARE OF 250 MW CAPACITY.

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Margins provided by OEM

• Continuous peak plant load duty (over and above
  the 100 unit MCR rating) is denoted equipment
  wise as follows
• Boilers BMCR (boiler MCR) rating
• Turbines VWO (valve wide open) rating
• Generators MVA (apparent power) rating
• Generating transformers MVA (apparent power)
  rating

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Margins over 250 MW

• DTPS units have operating margins of
• 8 steam flow in the boiler side (BMCR flow)
• 5 power output on the turbine side (VWO flow)
• 16 on the generator side (capability curve)
• 23 on the generator transformer side.
• These margins are provided in all 250 BHEL
  supplied units including those at Paras Unit 3,
  Parli Unit 6 and Tata Trombay Unit 8 as
  elaborated in the text. MARGINS CAN BE FULLY USED
  CONTINUOUSLY PROVIDED PARAMETERS ARE NOT
  EXCEEDED. OEM HAS IMPOSED RESTRICTIONS ONLY ON
  OPERATING PARAMETERS OF INDIVIDUAL EQUIPMENT AND
  NOT ON MW MARGINS

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BOILER MARGINS
Sl. No. Unit particulars-boiler UNITS NCR BMCR MARGIN Design
1 Dahanu 250 MW Units 1 2 t/h 746.60 805 1.08 CE/BHEL
2 Paras 250 MW Unit 3 t/h 736.20 810 1.10 CE/BHEL
3 Parli 250 MW Unit 6 t/h 738.21 810 1.10 CE/BHEL
4 Tata Trombay Unit 8 t/h 736.20 810 1.10 CE/BHEL
5 Nasik 210 MW Unit 5 t/h 652 700 1.07 CE/BHEL
6 Chandrapur 210 MW Unit 3 t/h 652 700 1.07 CE/BHEL
7 Bhusawal 210 MW Unit 3 t/h 654 700 1.07 CE/BHEL
8 Koradi 210 MW Unit 7 t/h 652 700 1.07 CE/BHEL
9 Khaperkheda 210 MW Unit No 4 t/h 624.23 690 1.11 CE/BHEL
10 Chandrapur 500 MW Unit 7 t/h 1540 1670 1.08 CE/BHEL
INSTALLATIONS at SL. Nos.5-10 are old
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• Plant load (active power or MW) dependent and
  plant load independent parameters
• Majority of the quality parameters like
  temperature, pressure (except for variable
  pressure operation), voltage, etc., are designed
  by the OEM to be nearly constant and first order
  load independent for the load range of 60 UMCR
  to through maximum load and changes are only
  second order.
• However, the quantity parameters like flow,
  current, etc. are directly proportional to
  active power (MW) or plant load or machine
  loading. As energy efficiency increases these
  quantities decrease in magnitude for a given
  output.

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• OEM DEFINITION OF
• CONTINUOUS PEAK
• LIMITED TIME PEAK PARAMETERS

• Continuous peak parameter purposefully set for
  achieving the maximum performance or output from
  the machine.
• Peak parameters for limited periods time limits
  in s /min /h in one excursion as well as total
  time in the lifetime of the equipment. Occurs
  because of system operational transients or
  constraints or faults or system mismatch.

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Sl. No. Particulars at 100 BMCR conditions Units Dahanu 250 MW Paras 250 MW Parli 250 MW Unit 6 Nasik 210 MW Unit 5 Chandrapur 210 MW Unit 3 Bhusawal 210 MW Unit 3 Koradi 210 MW Unit 7 Khaperkheda 210 MW Unit No 4 Chandrapur 500 MW Unit 7
1 Design coal GCV kcal/kg 3700 3400 3400 5000 4445 5100 5000 3500 3500
2 Annual average GCV kcal/kg 3966 3652 3608 3422 3170 3235 3642 3354 3170
3 Total heat to boiler Mcal/h 599.4 611.7 527.34 536 533.4 531.42 527.5 515.55 1215.9
4 Total fuel quantity t/h 162 179.9 155.1 107.2 120 104.2 105.5 147.3 347.4
5 Restriction on BMCR to GCV less No No No Yes No Yes Yes No No
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SIMULATED FROM ACTUAL DATA
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SIMULATED FROM ACTUAL DATA
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SIMULATED FROM ACTUAL DATA
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SIMULATED FROM ACTUAL DATA
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TURBINE MARGINS
Sl. No. Unit particulars-Steam turbine UNITS TMCR VWO MARGIN Design
1 Dahanu 250 MW Units 1 2 MW 250 262.82 1.05 Seimens
2 Paras 250 MW Unit 3 MW 250 264.78 1.06 Seimens
3 Parli 250 MW Unit 6 MW 250 264.78 1.06 Seimens
4 Tata Trombay Unit 8 MW 250 264.78 1.06 Seimens
5 Nasik 210 MW Unit 5 MW 210 213.30 1.02 Russian
6 Chandrapur 210 MW Unit 3 MW 210 215.80 1.03 Russian
7 Bhusawal 210 MW Unit 3 MW 210 215.00 1.02 Russian
8 Koradi 210 MW Unit 7 MW 210 215.80 1.03 Russian
9 Khaperkheda 210 MW Unit No 4 MW 210 221.70 1.06 Seimens
10 Chandrapur 500 MW Unit 7 MW 500 524.40 1.05 Siemens
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TURBINE MARGINS
Sl. No. Unit particulars - Steam turbine UNITS TMCR VWO MARGIN
1 Hitachi MW 210 222.00 1.06
2 Mitsubishi MW 210 222.00 1.06
3 Siemens MW 210 221.70 1.06
4 Russian MW 210 215.60 1.03
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VWO 800 t/h
SIMULATED FROM ACTUAL DATA
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VWO 800 t/h
SIMULATED FROM ACTUAL DATA
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TURBINES

• DTPS has be able to maintain good MW load ability
  on the machine within the OEM margins and without
  exceeding any OEM parameter limits by
• Maintaining high turbine efficiency (turbine heat
  rate deviates from design by only 4.4 kcal/kWh)
• Strictly maintaining water quality parameters as
  per OEM guidelines
• Minimizing auxiliary stack, vent and gland
  sealing steam requirements in the turbine.

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Sl. No. Unit particulars-Generator MVA rating MW at pf 0.85 MW at pf0.99 MARGIN pf0.85 to 0.99
1 Dahanu 250 MW Units 1 2 294.0 250 291.18 1.16
2 Paras 250 MW Unit 3 294.1 250 291.18 1.16
3 Parli 250 MW Unit 6 294.1 250 291.18 1.16
4 Tata Trombay Unit 8 294.1 250 291.18 1.16
5 Nasik 210 MW Unit 5 247.0 210 244.59 1.16
6 Chandrapur 210 MW Unit 3 247.0 210 244.59 1.16
7 Bhusawal 210 MW Unit 3 247.0 210 244.59 1.16
8 Koradi 210 MW Unit 7 247.0 210 244.59 1.16
9 Khaperkheda 210 MW Unit No 4 247.0 210 244.59 1.16
10 Chandrapur 500 MW Unit 7 588.0 500 582.35 1.16
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TESTS ON UNITS

• Maximum load- 265.5 MW 2292.7kcal/kWh
• 100 UMCR- 252 MW 2299.13 kcal/kWh
• F-GRADE LOAD- 2326.2 kcal/kWh
• MAXIMUM LOAD REACHED WAS 240 MW
• Design 2230.60 kcal/kWh
• Achieved 2293 kcal/kWh
• EVEN AT 268 MW NO PARAMETER HAS EXCEEDED OEM
  LIMITS DTPS CONTROL SET POINTS ARE BELOW OEM
  LIMITS

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Loadability

• Combining all the margins provided by the OEM,
  R-Infra has been able to load the unit to 268 MW
  against the design value of 250 MW.
• Maintaining this load is not harming the life of
  the unit as the DTPS has ensured that all
  parameters are kept within OEM limits.
• High loadability is made possible by high energy
  efficiency or low unit heat rate which enables
  the parameters not to exceed their limits.
• OEM MANUALS DO NOT SPECIFIC ANY UPPER LIMITS ON
  MW LOADING OR MW OVERLOADING ABOVE 100 UMCR
  RATING, OEM MANUAL SPECIFIES CONTINUOUS AND
  LIMITED TIME LIMITS ON OPERATING PARAMETERS OF B,
  T,G,GT, ETC.

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Remaining life

• Units 1 2 have been commissioned in Jan and
  March 1995 and have completed 15 years of service
  and nearly 1,20,000 operating hours.
• Acceleration of life expenditure takes place
  due to parameter excursions into the
  limited-time-overload-regime for long periods,
  due to frequent cyclic loading, due to frequent
  transients with high ramping rates. Scrutiny of
  operation and parameters indicates that the DTPS
  has avoided operation in these life limiting
  regimes thereby preserving the longevity of their
  assets. The cyclic operations are far lower than
  their design values.

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We are here
Remaining Life (h, years)
? lt45 Good
? gt 45 poor
?45 Normal
Real time years
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Remaining life

• Considering a total engineering life of 35
  years of service or 3,00,000 operating hours the
  physical (actual) life expenditure of both units
  is expected to be 40 . Except for generator,
  where the life expenditure is 50 (remaining
  life 50 or 14 years), the remaining life of
  other components matches roughly with the
  physical life expenditure.
• This indicates that acceleration of life has not
  taken place. The low degradation rate coupled
  with the high loading on the plant also leads to
  the conclusion that the equipment are healthy and
  factors in the nature of non-repairable damage
  are not present. UNHEALTHY EQUIPMENT CANNOT BE
  LOADED AT ALL

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Degradation

• The CPRI test TG HR is showing a degradation
  rate of 0.13 /year. The degradation is 2.0 of
  the DHR

LOW LEVEL OF DEGRADATION INDICATES THAT THE
EQUIPMENT ARE HEALTHY AND NO NEGATIVE EFFECTS OF
MW LOADING BEYOND 100 UMCR
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Up-rating/de-rating

• The maximum load on Unit 1 was 268.7 MW and
  on Unit 2 was 266.0 MW in 2009 in 2010.
  Up-rating or de-rating of the unit has been
  studied and it is concluded that the unit
  capacity is 250 MW and the present maximum plant
  loading of 268 MW is sustainable only because of
  high boiler, turbine and generator efficiency
  and external factors like coal quality being 600
  kcal/kg higher and high power factor of 0.99. The
  sustainability may not be long lasting.
• The PG test by OEM is for 250 MW, these units are
  identical to several 250 MW units, grid code 2005
  stipulates a margin over the 100 UMCR rating.
  Considering these facts it is concluded that the
  up-rating of 250 MW to 260 or 265 MW may not be
  sustainable in terms of availability as well as
  loadability in the future.

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CONCLUSIONS

• SCRUTINY OF RECORDS INDICATES UNIT CAPACITY IS
  250 MW IDENTIAL TO OTHER 250 MW UNITS SUPPLIED BY
  BHEL.
• OEM MARGINS IN BOILER, TURBINE, GENERATOR AND
  GENERATOR TR HAVE BEEN FULLY MADE USE OF TO
  ACHIEVE LOADABILITY OF 268 MW WELL WITHIN OEM
  PARAMTER LIMITS.
• OEM MARGINS CAN BE FULLY USED CONTINUOUSLY
  PROVIDED PARAMETERS ARE NOT EXCEEDED. OEM HAS
  IMPOSED RESTRICTIONS ONLY ON OPERATING PARAMETERS
  OF INDIVIDUAL EQUIPMENT AND NOT ON MW MARGINS.
  OEM PARAMTERS ARE NOT EXCEEDED BY DTPS.
• TESTS INDICATE ANNUAL UHR OF
• 265.5 MW - 2293 kcal/kWh
• 100 UMCR- 252 MW 2299.13 kcal/kWh
• F-GRADE LOAD- 2326.2 kcal/kWh
• MAXIMUM LOAD REACHED WAS 240 MW
• Design 2230.60 kcal/kWh
• Achieved STATION DATA 2293 kcal/kWh

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CONCLUSIONS

• UPRATING OF THE UNIT HAS BEEN STUDIED. SINCE THE
  UNIT IS OF 250 MW STANDARD DESIGN OF BHEL, THE
  MARGINS ARE BEING UTILIZED BY ENERGY EFFICIENCY
  IMPROVEMENTS, HIGHER GCV OF COAL AND HIGH POWER
  FACTOR. THESE CIRCUMSTANCES MAY NOT BE
  SUSTAINABLE ALL THROUGH THE LIFE OF THE UNIT.
• GENERATORS AND GTS ARE QUITE HEALTHY AND NORMAL.
  REMAINING LIFE IS ALSO GOOD. NO IMMEDIATE RISK
  FOR 16-20 khours AS PER THE RLA REPORTS OF ABB
  ERDA. CONSIDERING THE CRITICALITY OF LOAD
  HANDLED BY DTPS AND CONSIDERING THAT THERE ARE NO
  SPARES WITH OTHER MEMBERS OF MAHARASHTRA GRID FOR
  250 MW THESE CAN BE CONSIDERED.

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• THANK YOU