ENERGY AUDIT AT R-ENERGY AUDIT AT R-INFRA DAHANUINFRA DAHANU

THERMAL POWER STATION THERMAL POWER STATION (250 X 2 MW UNIT)(250 X 2 MW UNIT)

CENTRAL POWER RESEARCH CENTRAL POWER RESEARCH INSTITUTE, BANGALORE-560080INSTITUTE, BANGALORE-560080

MERC CONTRACT TO CPRIMERC CONTRACT TO CPRI

INVESTIGATION INTO PERFORMANCE OF INVESTIGATION INTO PERFORMANCE OF DTPS R-INFDTPS R-INF

PERIOD: 2 MONTHS FROM 22.01.2010PERIOD: 2 MONTHS FROM 22.01.2010 TOR: RATING OF THE UNITS TOR: RATING OF THE UNITS

PERMISSIBLILITY OF MW OVERLOADING OF PERMISSIBLILITY OF MW OVERLOADING OF THE UNIT ABOVE THE MCR VALUETHE UNIT ABOVE THE MCR VALUE

DE-RATING/UP-RATING OF THE UNITSDE-RATING/UP-RATING OF THE UNITSFACT FINDING OF UNIT CAPACITY & HISTORYFACT FINDING OF UNIT CAPACITY & HISTORYTESTS ON UNITS & CONSTRAINTSTESTS ON UNITS & CONSTRAINTS

DESIGN CAPACITY/ DESIGN CAPACITY/ RATING OF DTPSRATING OF DTPS

INSTALLED DURING BSES PERIOD 1995INSTALLED DURING BSES PERIOD 1995 TAKEN OVER BY R-INFRA IN 2003TAKEN OVER BY R-INFRA IN 2003 NO MAJOR CHANGE IN HARDWARE SINCENO MAJOR CHANGE IN HARDWARE SINCE IDENTICAL TO OVER 25 250 MW UNITS INSTALLED ALL IDENTICAL TO OVER 25 250 MW UNITS INSTALLED ALL

OVER INDIA INCLUDING PARLI, PARAS & TATA OVER INDIA INCLUDING PARLI, PARAS & TATA TROMBAY. TROMBAY.

SAME DESIGN REPLICATED IN ALL UNITS. THEY ARE OF SAME DESIGN REPLICATED IN ALL UNITS. THEY ARE OF STAND 250 MW DESIGN OF BHEL STAND 250 MW DESIGN OF BHEL

PG TEST, INSTALLATION MANUALS, NAME PLATES, PG TEST, INSTALLATION MANUALS, NAME PLATES, CAPACITY TESTS OF EQUIPMENT AND C & I INDICATE CAPACITY TESTS OF EQUIPMENT AND C & I INDICATE UNITS ARE OF 250 MW CAPACITY.UNITS ARE OF 250 MW CAPACITY.

Continuous peak plant load dutyContinuous peak plant load duty (over (over and above the 100 % unit MCR rating) and above the 100 % unit MCR rating) is denoted equipment wise as follows:is denoted equipment wise as follows:

Boilers: BMCR (boiler MCR) ratingBoilers: BMCR (boiler MCR) rating Turbines: VWO (valve wide open) ratingTurbines: VWO (valve wide open) rating

Generators: MVA (apparent power) Generators: MVA (apparent power)

ratingrating Generating transformers: MVA Generating transformers: MVA

(apparent power) rating (apparent power) rating

Margins provided by OEMMargins provided by OEM

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

Sl. No. Unit particulars-boiler UNITS NCR BMCR MARGIN Design

1Dahanu 250 MW Units 1 & 2 t/h

746.60 805 1.08 CE/BHEL

2Paras 250 MW Unit 3 t/h

736.20 810 1.10 CE/BHEL

3Parli 250 MW Unit 6

t/h738.2

1 810 1.10 CE/BHEL

4Tata Trombay Unit 8 t/h

736.20 810 1.10 CE/BHEL

5Nasik 210 MW Unit 5 t/h 652 700 1.07 CE/BHEL

6Chandrapur 210 MW Unit 3 t/h 652 700 1.07 CE/BHEL

7Bhusawal 210 MW Unit 3 t/h 654 700 1.07 CE/BHEL

8Koradi 210 MW Unit 7 t/h 652 700 1.07 CE/BHEL

9Khaperkheda 210 MW Unit No 4 t/h

624.23 690 1.11 CE/BHEL

10Chandrapur 500 MW Unit 7 t/h 1540 1670 1.08 CE/BHEL

BOILER MARGINS

INSTALLATIONS at SL. Nos.5-10 are old

Plant load (active power or MW) dependent Plant load (active power or MW) dependent and plant load independent parameters:and plant load independent parameters:

MMajority of the quality parameters like ajority of the quality parameters like temperature, pressure (except for variable temperature, pressure (except for variable pressure operation), voltage, etc., are designed pressure operation), voltage, etc., are designed by the OEM to be nearly constant and first by the OEM to be nearly constant and first order load independent for the load range of 60 order load independent for the load range of 60 % UMCR to through maximum load and % UMCR to through maximum load and changes are only second order. changes are only second order.

However, the quantity parameters like flow, However, the quantity parameters like flow, current, etc. are directly proportional to active current, etc. are directly proportional to active power (MW) or plant load or machine loading. power (MW) or plant load or machine loading. As energy efficiency increases these quantities As energy efficiency increases these quantities decrease in magnitude for a given output.decrease in magnitude for a given output.

Continuous peak parameter: Continuous peak parameter: purposefully set for achieving the purposefully set for achieving the maximum performance or output from maximum performance or output from the machine.the machine.

Peak parameters for limited periodsPeak parameters for limited periods: : time limits in s /min /h in one excursion time limits in s /min /h in one excursion as well as total time in the lifetime of the as well as total time in the lifetime of the equipment. Occurs because of system equipment. Occurs because of system operational transients or constraints or operational transients or constraints or faults or system mismatch.faults or system mismatch.

OEM DEFINITION OF: OEM DEFINITION OF: CONTINUOUS PEAK CONTINUOUS PEAK LIMITED TIME PEAK PARAMETERSLIMITED TIME PEAK PARAMETERS

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 536533.

4531.42

527.5

515.55

1215.9

4 Total fuel quantity

t/h 162 179.9 155.1 107.2 120 104.2105.

5147.

3347.4

5 Restriction

on BMCR to GCV

% less No No No Yes No Yes Yes No No

Variation of Steaming rate with boiler efficiency at constant coal consumption and constant GCV

740

750

760

770

780

790

800

810

80 82 84 86 88 90

Boiler efficiency, %

Ste

amin

g ra

te, t

/h

SIMULATED FROM ACTUAL DATASIMULATED FROM ACTUAL DATA

Variation of coal consumption with boiler efficiency at a constant boiler steaming rate and constant

GCV

150

152

154

156

158

160

162

164

80 82 84 86 88 90

Boiler efficiency, %

Co

al co

nsu

mp

tio

n, t/h

SIMULATED FROM ACTUAL DATASIMULATED FROM ACTUAL DATA

Dependence of unit loading (MW) on the coal quality

y = -4E-05x2 + 0.351x - 465.57

R2 = 0.7627

230

240

250

260

270

280

3300 3500 3700 3900 4100 4300 4500

Coal GCV (kcal/kg)

Un

it l

oad

(M

W)

SIMULATED FROM ACTUAL DATASIMULATED FROM ACTUAL DATA

Heat loading rate (Million kcal/h) in the boiler

480

500

520

540

560

580

600

620

640

235 240 245 250 255 260 265 270 275

Plant load (MW)

Hea

t loa

ding

rat

e (1

06 k

cal/h

)

design

Operating

Linear (design)

Linear (Operating)

SIMULATED FROM ACTUAL DATASIMULATED FROM ACTUAL DATA

Sl. No.

Unit particulars-Steam turbine UNITS

TMCR VWO

MARGIN Design

1

Dahanu 250 MW Units 1 & 2

MW 250262.8

2 1.05 Seimens

2

Paras 250 MW Unit 3

MW 250264.7

8 1.06 Seimens

3

Parli 250 MW Unit 6

MW 250264.7

8 1.06 Seimens

4

Tata Trombay Unit 8

MW 250264.7

8 1.06 Seimens

5

Nasik 210 MW Unit 5

MW 210213.3

0 1.02 Russian

6

Chandrapur 210 MW Unit 3

MW 210215.8

0 1.03 Russian

7

Bhusawal 210 MW Unit 3

MW 210215.0

0 1.02 Russian

8

Koradi 210 MW Unit 7

MW 210215.8

0 1.03 Russian

9

Khaperkheda 210 MW Unit No 4

MW 210221.7

0 1.06 Seimens

10Chandrapur 500 MW Unit 7 MW 500 524.40 1.05 Siemens

TURBINE MARGINS

Sl. No.

Unit particulars - Steam turbine UNITS

TMCR VWO MARGIN

1

Hitachi

MW210 222.00 1.06

2

Mitsubishi

MW210 222.00 1.06

3

Siemens

MW210 221.70 1.06

4

Russian

MW210 215.60 1.03

TURBINE MARGINS

Variation of steam input with turbine heat rate at constant power output

735

740

745

750

755

760

765

1920 1940 1960 1980 2000

Turbine heat rate, kcal/kWh

Ste

am

inp

ut t

o tu

rbin

e,

t/h

SIMULATED FROM ACTUAL DATASIMULATED FROM ACTUAL DATA

VWO: 800 t/h

Variation of power output with turbine heat rate at constant steam input to turbine

254

256

258

260

262

264

1920 1940 1960 1980 2000

Turbine heat rate, kcal/kWh

Po

we

r o

utp

ut, M

W

SIMULATED FROM ACTUAL DATASIMULATED FROM ACTUAL DATA

VWO: 800 t/h

TURBINESTURBINESDTPS 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.

Sl. No.

Unit particulars-Generator

MVA rating

MW at pf = 0.85

MW at pf=0.99

MARGIN pf=0.85 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

10Chandrapur 500 MW Unit 7

588.0 500

582.35 1.16

TESTS ON UNITS TESTS ON UNITS

Maximum load- 265.5 MW: 2292.7Maximum load- 265.5 MW: 2292.7kcal/kWhkcal/kWh

100 % UMCR- 252 MW: 2299.13 100 % UMCR- 252 MW: 2299.13 kcal/kWhkcal/kWh

F-GRADE LOAD- 2326.2 F-GRADE LOAD- 2326.2 kcal/kWhkcal/kWh

MAXIMUM LOAD REACHED WAS 240 MWMAXIMUM LOAD REACHED WAS 240 MWDesign: 2230.60 Design: 2230.60 kcal/kWhkcal/kWh

Achieved: 2293 Achieved: 2293 kcal/kWhkcal/kWh

EVEN AT 268 MW NO PARAMETER HAS EVEN AT 268 MW NO PARAMETER HAS EXCEEDED OEM LIMITS ; DTPS CONTROL EXCEEDED OEM LIMITS ; DTPS CONTROL SET POINTS ARE BELOW OEM LIMITSSET POINTS ARE BELOW OEM LIMITS

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 High loadability is made possible by high energy efficiency or low unit heat rate which enables the efficiency or low unit heat rate which enables the parameters not to exceed their limits.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.

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.

RemainingRemainingLife Life (h, years)(h, years)

Real time years Real time years

We are hereWe are here

ӨӨ <45<45˚̊

GoodGoodӨӨ > 45˚ > 45˚poorpoor

ӨӨ=45˚=45˚NormalNormal

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

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

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.

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 OEM MARGINS CAN BE FULLY USED CONTINUOUSLY PROVIDED PARAMETERS ARE NOT EXCEEDED. OEM HAS PROVIDED PARAMETERS ARE NOT EXCEEDED. OEM HAS IMPOSED RESTRICTIONS ONLY ON OPERATING IMPOSED RESTRICTIONS ONLY ON OPERATING PARAMETERS OF INDIVIDUAL EQUIPMENT AND NOT ON PARAMETERS OF INDIVIDUAL EQUIPMENT AND NOT ON MW MARGINS. MW MARGINS. OEM PARAMTERSOEM PARAMTERS ARE NOT EXCEEDED BY ARE NOT EXCEEDED BY DTPS.DTPS.

TESTS INDICATE ANNUAL UHR OF: 265.5 MW - 2293 kcal/kWh 100 % UMCR- 252 MW: 2299.13 kcal/kWh100 % UMCR- 252 MW: 2299.13 kcal/kWh F-GRADE LOAD- 2326.2 kcal/kWhF-GRADE LOAD- 2326.2 kcal/kWh MAXIMUM LOAD REACHED WAS 240 MWMAXIMUM LOAD REACHED WAS 240 MW Design: 2230.60 kcal/kWhDesign: 2230.60 kcal/kWh Achieved STATION DATA : 2293 kcal/kWhAchieved STATION DATA : 2293 kcal/kWh

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.