1. ENERGY AUDIT
METHODOLOGY FOR
FOR TURBINE CYCLE
Presented By
M.V.Pande
Dy.Director
NPTI, Nagpur

2. COAL TO ELECTRICITY PROCESS

3. STEAM CYCLE FOR 210 MW UNIT

4. EFFECT OF STEAM PARAMETERS
Effect of Increasing
Steam Temperature
On Available Energy
Effect of Increasing
Pressure on Available
Energy
Effect of Increasing
Steam Pressure &
Temperature Both on
Available Energy
P1
P2
P3
T1
P1
T2
T3
P1
P2
T1
T2
T1
H
S
H
S
S
H

5. EFFECT OF STEAM PARAMETERS
Effect of Changing Reheat Pressure Effect of Changing Reheat Temp.
S
S
H
H

6. THERMAL PROCESS LOSSES

7. 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 %
Impact of Turbine Cylinder Efficiency on
HR/Output
FOLLOW TEST CODES
• ASME PTC - 6 For Steam Turbines
• ASME PTC - 4.1 or BS- 845: 1987 for Boilers

8. 210 MW KWU STEAM TURBINE STEAM & WATER CYCLE

9. TURBINE CYCLE LOSSES

10. STEPS INVOLVED IN CONDUCTING THE
TURBINE ENERGY AUDIT
Data collection
Observations and Analysis
Exploration for energy conservation
measures
Report preparation

11. DATA COLLECTION
Design Specification of turbine and associated equipment:
 Type of the turbine, make and model
 Number of cylinders
 No of stages (for HP, IP and LP)
 No of main and reheat valves
 Construction details of HP, IP LP
 Turbine extraction systems
 Control systems
 Type of governing
 Type of sealing
 Year of installation
 Major modifications carried out during the recent past

12. DATA COLLECTION
Turbine Cycle Heat Rate Kcal/kwh

13. DATA COLLECTION

14. INSTRUMENTS REQUIRED
 Temperature Indicator & Probe
 Pressure gauges
 Flow measuring instrument (steam and
water)
 Ultrasonic leak detector

15. MEASUREMENTS & OBSERVATIONS TO BE MADE
 Feed water at Inlet & Outlet of Heaters
Main steam parameters
 HP turbine extraction
 Hot reheat steam, Cold reheat Steam
 IP extraction
 IP Exhaust
 Condenser back pressure
 Cooling water flow and temperatures
 Generator output
 Barometric pressure
 Reheater spray (flow)
 Superheater spray (flow)
 Feed water (flow)
Pressure
Temperature
Flow

16. MEASUREMENTS & OBSERVATIONS TO BE MADE
 Past performance trends on turbine loading,
operation, PLF
 Major constraint in achieving the high PLF, load or
efficiency
 Major renovation and modifications carried out in the
recent past
 Operational failures leading to inefficient operation
 Tripping
 Performance of associated equipment (condenser,
boiler, etc)
 Plant side initiatives to improve the performance and
efficiency of the Turbine

17. TURBINE HR EVALUATION AND EFFICIENCY
 Turbine heat rate is defined as the heat input (Kcal)
required to generate one unit of Electrical output (KWh). The
trials are to establish heat rate (Kcal/kWh) and turbine
efficiency under, as run conditions have to be carried out
 The efficiency method given in this procedure is the
enthalpy drop efficiency method. This method determines the
ratio of actual enthalpy drop across turbine section to the
isentropic enthalpy drop
 This method provides a good measure for monitoring
purposes. Each section of the turbine must be considered as
a separated turbine
 Each section should be tested and results are trended
separately. While conducting the tests, it has to be ensured
that, it is conducted over normal operating load range

18. TURBINE HR EVALUATION AND EFFICIENCY
Turbine Cycle Efficiency =
860
Heat Rate
X 100
kW
kCal/hr
Turbine Heat Rate =
Q1
x (H1
– h2
) + Q2
X (H3
– H2
)
Gross Generator Output

19. TURBINE HR EVALUATION AND EFFICIENCY
Comparison of Actual Expansion
with Isentropic Expansion in
Turbine
Actual Expansion in HP, IP & LP
Cylinder
Actual
Process
1-2-3-4-5

20. TURBINE HR EVALUATION AND EFFICIENCY
Heat Rate Characteristics with
Condenser Exhaust Pressure
Variation of Heat Rate with Load

21. TURBINE EFFICIENCY EVALUATION DATA
Kcal/kg/oK

22. Effect of Condenser Vacuum on
Heat Rate
10 MM HG IMPROVEMENT IN
CONDENSER VACUUM
LEADS TO 20 Kcal/kwh (1%)
IMPROVEMENT IN HEAT RATE FOR A
210 MW UNIT

23. EFFECT ON HEAT RATE FOR PARAMETER
DEVIATION (500 MW UNIT)
DEVIATION IN PARAMETER EFFECT ON HEAT
RATE (KCAL/KWH)
1. HPT inlet press. by 5.0 ata 6.25
2. HPT inlet temperature by 10.0 deg C 6.0
3. IPT inlet temperature by 10.0 deg C 5.6
4. Condenser pressure by 10.0 mm of Hg 9.0
5. Re spray water quantity by 1.0% 4.0
6. HPT Cylinder efficiency by 1.0% 3.5
7. IPT Cylinder efficiency by 1.0% 4.0

24. IDENTIFYING FACTORS FOR HR DEVIATION
After evaluating the turbine heat rate and efficiency,
check for the deviation from the design and identify the
factors contributing for the deviations. The major factors
to be looked into are:
 Main steam and reheat steam inlet parameters
 Turbine exhaust steam parameters
 Reheater and super heater spray
 Passing of high energy draining
 Loading on the turbine
 Boiler loading and boiler performance
 Operations and maintenance constraints

25. IDENTIFYING FACTORS FOR HR DEVIATION
 Condenser performance and cooling water parameters
 Silica deposition and its impact on the turbine efficiency
 Inter stage sealing, balance drum and gland sealing
 Sealing fins clearances
 Nozzle blocks
 Turbine blade erosion
 Functioning of the valves
 Operational status of HP heaters
 Performance of reheaters

26. FEED WATER HEATERS PERFORMANCE
inlet
inlet
outlet
0 C

27. FEED WATER HEATERS PERFORMANCE
While collecting the heater wise parameters, collect
the following data:
 Unit load MW
 Main steam pressure, temperature & flow
 Feed water flow
 Super heater & Reheater attemperation flow
 Boiler feed pump discharge pressure
 HP Heater levels
 Condenser vacuum, Barometric pressure

28. FEED WATER HEATERS PERFORMANCE
After the collecting the above data, evaluate the following
 Terminal temperature difference – TTD
 Heater drain cooler approach temperature difference – DCA
 Feed water temperature rise across heater – TR
TTD = t sat – t fw outlet

29. FEED WATER HEATERS PERFORMANCE
DCA = t drains – t fw inlet
TR = t outlet – t fw inlet

30. HEATER PERFORMANCE DEVIATION
Check following if TTD, DCA, TR are deviating from the
design and actual rise in feed water temperature is low:
High terminal temperature difference, TTD
 Excessive venting (worn vents, altered set point, vent
malfunctioning)
 Excessive make up
 High water level (tube leaks, improper setting)
 Header partition leaks
 Non condensable gases on shell side
 Excessive tube bundle pressure drop (excessive number of
tubes plugged, tubes folded internally)

31. HEATER PERFORMANCE DEVIATION
High drain cooler approach temperature, DCA
 Drain cooler inlet not submerged
 Low drain water level (improper setting, excessive FW
heater drain bypass – bypass valve left open - bypass valve
malfunctioning / leaking)
 Excessive tube bundle pressure drop (excessive number
of tubes plugged / tubes folded internally)
 Feed water heater bypassed
 FW heater bypass valve leaking
Note: Similar approach shall be followed for LP Heaters

32. ADDITIONAL LOAD ON ECONOMIZER
Based on the above, if the HP heaters performance is poor,
then additional load on economizer can be estimated by using
the data sheet
economizer