The document discusses turbine performance and efficiency in power plants, focusing on cycle efficiency and heat rate calculations. It details the main components that affect turbine cycle efficiency and addresses common myths related to efficiency testing. Additionally, it outlines the methodology for measuring turbine parameters and highlights the impact of turbine efficiency on heat rates and operating costs.

1. TURBINE PERFORMANCE
“total output power solutions”
By
Manohar Tatwawadi
Pune, 411045

2. Turbine Cycle

4.  Generally Cycle Efficiency of a power Plant is in
the range of 38 %
 Major components affecting the Turbine Cycle
Efficiency are
 HP / IP /LP Turbine
 Condenser
 HP Heaters
Cycle Performance

5. TURBINE CYCLE
HEAT RATE

6.  Turbine Cycle Heat rate depends upon, how
much heat is utilized for generation of one unit
GTCHR = Heat added to Cycle / Total mw
generated
Performance of Turbine & Aux.

7. Heat Added to cycle :
Heat Added MS
= Flow MS * (hMS - hFW), kcal/hr
Heat added by SH Attemp
= Flow SH Attemp* (hMS-hSHATT) Kcal/hr
Heat Added CRH
= Flow CRH* (hHRH - hCRH),kcal/hr
Heat added by RH Attemp
= Flow RH Attemp * (hHRH-hRHATT) Kcal/hr
Performance of Turbine & Aux.

8. How to Know Turbine Cycle Heat Rate ?

9. Turbine Cycle Heat Rate can be calculated
based upon
1. On line Instrument Testing
2. Off line Instrument Testing

10. Myth about Efficiency Testing ?

11. Myths
 Efficiency tests are the same as performance
guarantee test.
 Heat rate improvement requires large
investment.
 Results follow immediately after testing is
completed.
 Heat rate is the responsibility of operation and
efficiency cell of plant.
 Station instruments are accurate for monitoring
heat rate parameters.

12. Myths contd…
 Efficiency tests require deployment of large
manpower.
 Renovation and modernization (R&M) will take care of
efficiency and should precede any heat rate
improvement efforts by plant.
 Manufacturer has more knowledge of equipment and
should be involved in the efficiency test.

13. Turbine Cycle Testing

14. Instruments required for Turbine Cycle HR
Test
Measurement Temperature Pressure
MS 2 2
CRH 2 2
HRH 2 2
FW at Eco Inlet 1 1
FW Flow -- 1 (dp)
SH Spray -- 1 (dp)
RH Spray -- 1 (dp)
Unit Load -- --

16. 1 Gross Load 13 FW Press HPH Inlet
2 MS Pressure before ESV 14 FW Temp HPH Inlet
3 MS Temp before ESV 15 FW Press HPH Outlet
4 HPT Exhaust Pressure 16 FW Temp HPH Outlet
5 HPT Exhaust Temp. 17 Main Steam Flow (Q1)
6 HRH Steam Press. before IV 18 Feed Water Flow (Qf)
7 HRH Steam Temp. before IV 19 CRH Flow (Q2)
8 FW press after top heater 20 S/H Spray Flow (Qs)
9 FW Temp at Eco inlet 21 R/H Spray Flow (Qr)
10 HPH Ext. Steam Temp 22 S/H Spray Temp.
11 HPH Shell Pressure 23 R/H Spray Temp.
12 HPH Drip Temp 24 Leak Off Flow
PARAMETERS TO BE MEASURED

17. Enthalpy of MS Kcal/Kg H1
Enthalpy at HPT Exhaust Kcal/Kg H2
Enthalpy at HRH Kcal/Kg H3
Enthalpy of FW at Eco.inlet Kcal/Kg h1
Enthalpy of HPH Ext Steam Kcal/Kg Hext
Enthalpy of FW Entering HPH Kcal/Kg Hin
Enthalpy of FW Leaving HPH Kcal/Kg Hout
Enthalpy of HPH drip Kcal/Kg Hdrip
Enthalpy of S/H Spray Kcal/Kg hs
Enthalpy of R/H Spray Kcal/Kg hr
PARAMETERS DERIVED FROM STEAM
TABLES

18. Total steam flow (Q1) = Feed Flow (Qf)+ S/H
Spray Flow (Qs)
Calculation of Main Steam Flow
Calculation of Reheat Steam Flow
CRH Flow (Q2) =
Steam Flow (Q1) – Extraction Flow (Qe) of HPH -
Leak Off steam flow
Leak off steam flow derived from design leak off flow

19. Qf (Hout – Hin)
Extraction Flow (Qe) =
(Hext – Hdrip)
Where: Qf = Feed Flow
Hout = Feed Water Enthalpy at HPH
Out.
Hin = Feed Water Enthalpy at HPH in
Qe = Extraction Flow
Hext = Enthalpy of Extraction Steam
Hdrip = Enthalpy of Drip
Calculation of Extraction Flow

20. Turbine Cycle Heat Rate (kcal/kWh) =
Qf (H1 - h1) + Qs (H1-hs)+Q2 (H3 - H2 )+ Qr (H3-hr)
Gross Load
Calculation Of Turbine Cycle Heat Rate

21. Precautions to be taken
Test Conditions
 Unit Off Load Control and Steady
 Main Steam Pressure at Design Value
 Main Steam and Reheat Steam Temperatures at
Current Expected Value
 Boiler Outlet O2 at Current Expected Value
 All Feed water Heaters in Service, Normal Levels
and Vent Settings, Normal Drain Routing
 No Auxiliary Steam Cross Tie to Other Units.
 No Soot Blowing.
 Test Engineer to ensure the load is steady

22. Computation Error & Remedial action
Feed Flow :
One of the most important parameters measured in
any power plant is the fluid flow rate in the various
system and components. For Feed water flow there
are flow nozzles/orifice, the DP measurement
across the device is further used for flow
computation.
Flow measuring devices dp transmitter should be
calibrated every year.
Power Measurement :
Other most important parameters is the power
measurement . Power measuring devices should be
of high accuracy preferably 0.2 % accuracy class.

23. Test Result
Test GTCHR – 2156 kcal/kWh
Design GTCHR- 1981 kcal/kWh
Gap-175 kcal/kWh

24. Type of Losses
Accountable Loss- 133 kcal/kWh
Un accountable Loss – 42 kcal/kWh

25. HEAT RATE DEVIATION
STATION:
UNIT NO: DATE:
ParameterS.
N
Parameter Unit
Design Actual
HRD
1 Load MW
Accountable HR Deviation
2 Main steam Press before ESV kg/cm2
3 Main steam Temp before ESV ° C
4 Hot Reheat Temp before IV ° C
5 Superheat Attemperation t/hr
6 Reheat Attemperation t/hr
7 Condenser Back Pressure mm Hg
8 Makeup Water % MCR
9 FW temperature at HPH O/L ° C
10 HP Turbine Efficiency %
11 IP Turbine Efficiency %
12 (Total
Accountable HR Deviation)
Kcal/
kWh
13 Unaccountable HR Dev
(Test GTCHR-Design GTCHR-
Accountable)
Kcal/
kWh

26. Break Up of Accountable Losses
(133 kcal/kWh)
Description Loss
kcal/kwh
HP Turbine Eff. 15.81
IP Turbine Eff. 22.95
Cond. Vac. 19.75
HP Heater 5 & 6 41.48
RH Temp. 6.0

27. Unaccountable Losses
42 kcal/kWh
 High Energy drain Passing
 Instrument Error
 System Water Loss
 L.P. Turbine Performance
 L.P. Heaters

28. Methodology to reduce Unaccountable
High energy drains passing
• Installation of thermocouples on down stream
• Progressive replacement of High energy drain
valves
• Attending valves during opportunity shut down.
• Checking of valve of valve passing before O/H
• Joint checking by Operation & TMD after unit
startup
System Water Loss
• D/A drop test to be conducted periodically.
Instrument Error
• Use of accurate & calibrated Instrument

29. Effect of Parameter on HR Deviations – Test
Data
Gen
Load
Avg
Main
Steam
Temp
HR
Deviati
on for
MS
Temp
Avg
CRH
Temp
Avg Hot
Reheat
Temp
HR
Deviati
on for
HRH
Temp
RH
Attemp.
Spray
Flow
HR
Deviati
on for
RH Att
Avg IPT
Exh
Temp
MW C
kcal /
kWh C C
kcal /
kWh t / hr
kcal /
kWh C
Design 535 335.2 535 314
216.32 530.72 3.6 345.77 525.11 5.6 3.3 1.6 314.54
195.17 531.09 3.4 342.03 522.73 6.9 3.4 2.0 313.17
212.62 530.62 3.7 344.33 524.34 6.0 3.9 1.9 314.43
191.78 533.96 1.1 344.51 529.37 3.3 4.3 2.5 319.17
174.64 533.41 1.6 342.81 524.65 5.9 3.8 2.7 315.38
215.06 534.44 0.7 352.65 530.50 2.6 3.7 1.8 319.40
191.03 536.79 -1.1 358.22 536.26 -0.5 3.1 6.1 323.84
172.96 536.37 -0.8 357.94 532.09 1.8 3.7 2.6 321.95

30. HP/IP/LP Turbine
Efficiency

31. STEAM TURBINES ARE DEVICES WHICH CONVERT
THE ENERGY STORED IN STEAM INTO
ROTATIONAL MECHANICAL ENERGY.
First step is expansion of steam in nozzles, which
convert some of this heat & pressure energy in to
kinetic energy of steam jet.
In second step kinetic energy of the jet is used
with moving blades to change that energy into
useful mechanical energy.
Steam Turbine

32. Typical Combination

33. • TURBINE STAGE CATEGORIZATION :
* First Stage or Governing Stage
* Last Stage
* All the Stages in-between
 First Stage or Governing Stage :
* Change in flow changes First Stage Discharge
Pressure, resulting in change in pressure ratio
* Ideal ratio is at VWO
* First Stage efficiency decreases with closing of CV
 Last Stage :
* Upstream pressure changes with change in CV position
* Downstream pressure changes with condenser pressure
* Efficiency changes with both CV position & Cond. Press.
 All the Stages in-between :
* Pressure ratio is constant therefore constant efficiency
Stage Design Characteristics

34. Section Efficiency
* It depends on combined efficiency of each stage
* Typical values of efficiency
HP 86 %
IP 90 %
LP 88 %
* As steam expends from throttle to Condenser
pressure volume flow increases.
* Increase in volume flow increases blade radial
heights
* Efficiency improves with increase in blade height
since leakage losses are less w.r.t. total loss.
* LP Turbine efficiency is lower w.r.t. & IPT due to
wet region (latter stages).
* 1% effect on stage efficiency with 1% moisture.

35. 2 % change in HP or IP Turbine Efficiency in a
210 MW unit leads to change in HR by about
8 kcal/kWh and having cost implication of
about Rs 56 lakhs per year (rail fed station)
Effect of Turbine Efficiency
On
Heat Rate and O&M cost

36. Description Effect on Effect on
TG HR KW
1% HPT Efficiency 0.16% 0.3%
1% IPT Efficiency 0.16% 0.16%
1% LPT Efficiency 0.5 % 0.5 %
Output Sharing by Turbine Cylinders
HPT 28%
IPT 23%
LPT 49%
Impact of Turbine Efficiency on
HR/Output

37. Turbine
Performance
Assesment

38. Parameters to be Measured
Load MW
MS Pressure before ESV Kg/cm2(abs)
MS Temp. before ESV Deg.C
HPT Exhaust Pressure Kg/cm2(abs)
HPT Exhaust Temperature Deg.C
HRH Steam Press bef. IP Kg/cm2(abs)
HRH Steam Temp. bef. IP Deg.C
IPT Exhaust Steam Press Kg/cm2(abs)
IPT Exhaust Steam Temp. Deg.C
Turbine Efficiency Testing

39. The Number of Instruments required for
Turbine Efficiency Test
Measurement Temperature Pressure
MS 2 2
CRH 2 2
HRH 2 2
IPT Exhaust 2 2

42. Used Energy
Turbine Efficiency =
Available Energy
hin - hout
=
hin – hisen
Where
hin = Enthalpy at Cylinder Inlet conditions
hout = Enthalpy at Cylinder Outlet conditions
hisen = Isentropic Enthalpy

43. Load
(MW)
210
HPT Eff.
At CPO(%)
77.08
HPT Eff.
At VWO(%)
82.088
190 70.87 81.96
173 69 81.82

44. Problems in Performance Assessment
Generally HP/IP Efficiency calculated at stations
may have the following deficiencies:
 High variation in Efficiency if trend is plotted.
 HP/IP Efficiency worked out to be low after
O/H
 HP/IP Efficiency improves after O/H even
though Cylinder was not opened.
 Efficiency of HP/IP improves better than
design

45. Reasons For Assessment Error
Followings are the reasons for error in
computation of efficiency.
 HPT efficiency test not done at VWO
 Test set up is not same for all tests.
 Steady conditions of Unit is not achieved.
 Measurement points are not representative
 Measuring instruments are not accurate
 Necessary corrections like ambient pressure,
water leg not taken care

46. • Trending Efficiency
• Pressure ratio Comparison
• Ratio of Exhaust pressure to Inlet pressure
• Trending Pressure ratio of sections at Extraction
point
• Decrease in pressure ratio – chances of deposit
• Increase in pressure ratio – increase in
clearances / chances of erosion
Turbine Performance Monitoring

47.  Friction losses in stationary and rotating blades
 Erosion of nozzle blocks and turbine blades
 Seal leakages (Tip seal and inter-stage seals)
Factors Affecting Turbine
Efficiency Deterioration

48. LEAKAGE LOSS - 50%
SURFACE ROUGHNESS - 36%
OTHERS - 14%
Breakup Of Turbine
Efficiency Losses (%)

49. OTHERS
6%
SHAFT
SEALS
15%
INTER
STAGE
27%
TIP
SEALS
52%
Contribution Of Different Seals

50. DIAPHRAGM
TIP
SPILL STRIPS
BALANCE HOLE
W HEEL
PACKING
SHAFT
STEAM FLOW
ROOT
SPILL STRIPS
ROTATING
BLADE
STATIONARY
BLADESTAGE
PRESSURE
DOVETAIL
INTERSTAGE PACKING LEAKAGE
BALANCE HOLE
FLOW
ROOT LEAKAGE
TIP
LEAKAGE
COVER OR
SHROUD
TENON
Impulse Wheel and Diaphragm
Construction

51. ROTOR
TRAILING
EDGE
BLADE
CARRIER
LEADING
EDGE
INTERSTAGE
PACKING
TIP SPILL
STRIPS
STATIONARY
BLADE
ROTATING
BLADE
TENONTIP
LEAKAGE
COVER
Reaction Drum Rotor
Construction

52. Identification Of
Area Of Losses

53. Steam Path Audit

54. What is a Steam Path Audit?
A detailed inspection of the stationary and
rotating steam path components
An accounting of performance losses on a
stage-by-stage basis

55. Benefits of a SPA
√Provides detailed inspection of steam path
√Repair/replacement decisions, early in
outage
√Aid decisions for future repair
√Provides excellent record/history of
equipment condition for future reference

56. The specific areas of concern addressed
by the audit are:
1) Leakages:
- past stationary stage blading
- past rotating stage blading
- past shaft end packings where
rotors emerge from casings
- across poorly fitting joints
- other miscellaneous leakages
3) Flow blockages from:
- deposits
- foreign objects
- mechanical damage
2) Surface finish degradation:
- deposits
- corrosion
- solid particle erosion
- mechanical damage
4) Flow path modification
from:
- solid particle erosion
- water droplet erosion
- mechanical damage

57. √ Inspect casing horizontal joint for leakage paths
√ Measure blade geometry
√ Measure packing teeth, interstage, tip, root, and
& shaft end
Measurements & Observations
Casing Lifted

58. √Chart rotor for actual radial clearances
 Inter stage packings
 Shaft end packings
 Root spill strip clearances
 Tip spill strip clearances
Before Lifting Rotor
Measurements & Observations

59. √Measure lower half tooth heights
 Inter stage packing and shaft end packing
 Root and tip spill strips
√Inspect lower half diaphragms
 Surface roughness
 Solid particle erosion
 Mechanical damage
After Lifting Rotor
Measurements & Observations

60. Rotor
√Inspect rotating blades
Surface finish
Solid particle erosion
Mechanical damage
Cover deposits
Measurements & Observations

61. Geometric Data
√ Geometric data for the steam path must be
obtained to properly model turbine
Blade heights and widths
Blade root diameters
Balance holes
Measurements & Observations

62. Case Studies

63. HP/IP Turbine Efficiency Testing
HP Turbine Efficiency
 HPT Efficiency as per (HBD) 86.71%
 HPT Efficiency as per Test Data 82.08%
 Deterioration in HPT Efficiency 04.08%
IP Turbine Efficiency
√ IPT Efficiency as per HBD 90.58%
√ IPT Efficiency as per Test Data 81.62%
√ Deterioration in IPT Efficiency 8.96%

64. Turbine Efficiency Vs CV Position – Test
Data
Gen
Load
HP
Turbine
Efficiency
IP Turbine
Efficiency
CV
Position
MW % % %
Design 86.71 90.58 VWO
Run 1- CP 216.32 78.40 81.88 42/74
Run 2- CP 195.17 73.54 81.40 34/58
Run 3- CP 212.62 77.08 81.68 40/70
Run 4- CP 191.78 70.87 81.21 32/55
Run 5- CP 174.64 69.00 80.64 30/50
Run 1- VP 215.06 82.08 81.62 100
Run 2- VP 191.03 81.96 81.40 100
Run 3- VP 172.96 81.82 80.21 100

65. HP TUBINE EFFICIENCY
(CPO Vs VPO)
Load
(MW)
210
HPT Eff.
At CPO(%)
77.08
HPT Eff.
At VPO(%)
82.088
Gain
(%)
5
190 70.87 81.96 11.09
173 69 81.82 12.82
Note: HPCV 100% open at VPO

66. Load
MW
HR at
CPO
Kcal/kwh
HR at
VPO
Kcal/Kwh
Improvement
at VPO
Kcal/kwh
Gains/
Year
Rs. Lacs
210 2135 2113 22 124.08
190 2168 2114 54 304.56
173 2183 2120 63 355.32
High Gains in Adopting Variable
Pressure Operation (VPO)
*Power Saving by BFP - 426 kw at 173 mw Load

67. Thank You
Questions
Please ..