Heat rate is a key performance indicator for power plants that measures efficiency. It is calculated as the amount of input energy (e.g. coal) divided by the amount of electrical output energy. A lower heat rate indicates a more efficient plant. The document discusses different types of heat rates used - gross, net, and turbine cycle - and how to calculate them directly from energy inputs and outputs or indirectly based on deviations from design parameters. More advanced supercritical and ultra-supercritical plant designs have been able to achieve significantly lower heat rates and higher efficiencies compared to older subcritical plant designs.

1. Heat Rate

2. Heat rate is the pulse rate of a power plant to
know the health of the plant.
Net heat rate is the single parameter that
encompasses total performance indices of a
power plant.

3. Efficiency % = Output Energy X 100
Input Energy
Heat rate = Input Energy
Output Energy
Heat rate = 1
Efficiency %
1 kwh = 860 kcal
Some Basics to understand Heat Rate

4. Boiler
G
Turbine GT
UT-A
UT- B
Heat
Energy of
Coal
Heat
Energy of
Steam Gross
Elect.
Energy
Net
Elect.
Energy

5. Gross Unit Heat Rate
A “unit” heat rate includes all heat input to the boiler. The heat input to the boiler
should include all forms of chemical energy supplied and the “gross” electrical
generation
Net Unit Heat Rate
A “unit” heat rate includes all heat input to the boiler. The heat input to the boiler
should include all forms of chemical energy supplied and the “net” electrical
generation i.e., auxiliary power is to be subtracted from gross electrical energy
Gross Turbine Cycle Heat Rate (GTCHR)
A “Gross Turbine Cycle” heat rate includes only heat input to the turbine cycle. GTCHR
is the ratio of total heat input to the turbine cycle and the gross generator output
Design Unit Heat Rate
Design heat rate is anticipated heat rate at design parameters at specific load
condition like different MCR, VWO by manufacturer

6. Boiler
G
Turbine GT
UT-A
UT- B
Heat
Energy of
Coal
Heat
Energy of
Steam Gross
Elect.
Energy
Net
Elect.
Energy
Heat
Energy of
Coal
Gross Unit Heat Rate =
Gross
Elect.
Energy

7. Boiler
G
Turbine GT
UT-A
UT- B
Heat
Energy of
Coal
Heat
Energy of
Steam Gross
Elect.
Energy
Net
Elect.
Energy
Gross Turbine Cycle Heat Rate =
Gross
Elect.
Energy
Heat
Energy of
Steam

8. Boiler
G
Turbine GT
UT-A
UT- B
Heat
Energy of
Coal
Heat
Energy of
Steam Gross
Elect.
Energy
Net
Elect.
Energy
Heat
Energy of
Coal
Net Unit Heat Rate =
Net
Elect.
Energy

9. Boiler G
Turbine
2236 kcal
1944 kcal
1kwh
(860kacl)
Boiler G
Turbine
2248 kcal
1951 kcal
1kwh
(860kacl)
DESIGN HEAT RATE
600 MW
250 MW

10. Heat Rate Calculation
Heat Rate can be calculated as
1)Direct Method
2)Indirect Method

11. Direct Method
• Direct Method of Heat Rate Assessment is suitable for
long duration in which averaging gives almost actual Heat
Rate because Coal consumption measurement is fairly
accurate if taken over a month/Year.
• Therefore, this method is employed at almost all stations
as per the standard practice.
• The methodology adopted by CEA for assessment of
station heat rate is based on Direct Method

12. Gross Heat rate = Heat Energy of Coal (Kcal)
Gross Electrical Energy Generated(Kwh)
Gross Heat rate = Coal Consumption(kg) x GCV(Kcal/kg)
Gross Electrical Energy Generated(kwh)
Gross Heat rate = Specific Coal Consumption(kg/kWh) x GCV(Kcal/kg)
Direct Method

13. Gross Heat rate = Heat Energy of Coal (Kcal)
Electrical Energy Generated(Kwh)
Gross Heat rate = Heat Energy of Coal (Kcal) x Heat Energy of Steam(Kcal)
Electrical Energy Generated(Kwh) x Heat Energy of Steam(Kcal)

14. Gross Heat rate = Heat Energy of Coal (Kcal) x Heat Energy of Steam
Heat Energy of Steam x Electrical Energy Generated(Kwh)
Gross Turbine Heat rate = Heat Energy of Steam(Kcal)
Electrical Energy Generated(Kwh)
Boiler Efficiency % = Heat Energy of Steam(Kcal)
Heat Energy of Coal (Kcal)
Gross Heat rate = Gross Turbine Heat Rate
Boiler Efficiency %

15. Net Heat rate
Net Heat rate = Heat Energy of Coal (Kcal)
Net Electrical Energy (Kwh)
Net Heat rate = . Heat Energy of Coal (Kcal) .
{Gross Electrical Energy (Kwh)- Aux Power (kwh)} x Gross Electrical Energy(kwh)
Gross Electrical Energy(kwh)
Net Heat rate = Heat Energy of Coal (Kcal)
{Gross Electrical Energy (Kwh)- Aux Power(kwh)}
Net Heat rate = . Gross Unit Heat Rate(kcal/kwh)
{1 - Aux Power (kwh)}
Gross Elect. Generation(kwh)

16. Net Heat rate = . Gross Unit Heat Rate
{1 - Aux Power%}

17. Indirect Method
• Indirect method of Heat Rate Measurement is
an instantaneous method which is used for
short duration and not possible throughout
the year.
• It is a very complex method and basically a
loss based method of measurement of Heat
Rate.
• This method is generally adopted during the
Energy Audit Studies.

18. Indirect Method
• Gross Heat Rate = Design Heat rate + Heat rate losses(
Accountable + Unaccountable)
• Accountable Parameters – Parameters deviated from the
design values. Correction factors and general thumb
rules are applied to calculate.
• Accountable parameters are required to be operated
closest to design value to optimize heat rate.
• Unaccountable deviations are due to drain valve passing,
Instrument measurement errors, radiation losses etc.

19. Unit # : Date 12-Jul-15
Sl. No. Parameter Unit
Parameters
Heat Rate Deviation
Design Actual Deviation
Kcal/kwh
1 Load MW 600 409.6 -190.4 66.979
Accountable HR Deviation
2 Main Steam Press before ESV Kg/cm2 170 126.9 -43.1
3 Main Steam Temp before ESV o
C 537 537.8 0.8 -0.5
4 Hot Reheat Temp before IV o
C 537 525.4 -11.6 6.4
5 Reheat Attemperation TPH 0 2.33 2.3 1
6 Condenser back pressure mmhg 75.9 71.4 9.2 18.4
7 CW Inlet Tempertaure o
C 33 30.5 2.53 -15.2
8 Makeup Water % %MCR 0 0.084 0.08 0.5
9 FW Temperature at Eco I/L o
C 253.7 222.4 13.7 12.3
10
Dry Flue Gas Loss(DFG) % 4.5 5.6 1.1 27.9
Effect of Coal on DFG % 0.8
a) Oxygen at APH inlet % 3.6 4.1
b) APH Exit Temperature(Corrected) o
C 140 128.2
c) APH Leakage % 11.6
11
Wet flue Gas loss % 6.36 6.9 0.5 12.5
a) Moisture in coal % 2.33 2.4
b) % Hydrogen in coal % 3.85 4.4
12 Combustible in Fly ash % 0.21 -0.1 -3.3
13 Combustible in Bottom ash % 2.20 1.5 6.3
14 Startup oil consumption % 0 0 0.0
15 HP Turbine Cylinder Efficiency(VWO) % 92.36 90.98 1.38 6.1
16 IP Turbine Cylinder Efficiency % 93.16 91.62 1.54 6.8
17 Total Accountable HR deviation(A) Kcal/kwh 146
18 Unaccountable HR Deviation (B) Kcal/kwh 22
19 Total Heat Rate Deviation (A+B) Kcal/kwh 168
20
Expected Design HEAT RATE at Full
Load and Rated condition(C)
Kcal/kwh 2236
21 Goss Heat Rate (A+B+C) Kcal/kwh 2404
Aux Power consumption 6.5%
22 Net Heat Rate on the basis of coal Kcal/kwh 2572

20. Design Heat Rate for 600MW at various load
PLF Load Gross HR Aux Power Net HR Efficiency %
100.00% 600 2236 6 2379 36.15
95.00% 570 2244 6.25 2394 35.92
90.00% 540 2254 6.5 2411 35.67
85.00% 510 2266 6.75 2430 35.39
80.00% 480 2282 7 2454 35.04
75.00% 450 2300 7.25 2480 34.68
70.00% 420 2321 7.5 2509 34.28
65.00% 390 2346 7.75 2543 33.82
60.00% 360 2373 8 2579 33.35
55.00% 330 2403 8.25 2619 32.84
50.00% 300 2435 8.5 2661 32.32

21. y = 0.0016x2 - 2.0858x + 2918.7
2200
2250
2300
2350
2400
2450
0 100 200 300 400 500 600 700
Heat
Rate
(in
Kcal/Kwh)
Load in MW
LOAD VS GROSS HEAT RATE

22. Impact of Performance Parameters Deviations on
Heat Rate for 4 x 600 MW
Sl.No. Parameters Units Deviations
Average HR loss
kcal/kwh
1 HP Turbine Efficiency % 1 4.01
2 IP Turbine Efficiency % 1 3.78
3 LP Turbine Efficiency % 1 10.35
3 Main Steam Pressure Kg/cm2
(a) 1 1.33
4 Main Steam Temperature o
C 1 0.67
5 Reheat Temperature o
C 1 0.56
6 Reheat Spray TPH 10 2.23
7 Excess Air ( O2) % 1 6.64
8 Flue gas exit temperature o
C 1 1.2
9 Condenser pressure mmHg (a) 1 2
10 Unburned Carbon % 1 8.5
11 Coal Moisture % 1 4.4
12 DM Makeup % 1 7.76
13 FW Temperature o
C 1 0.8
15 HPH Out - - 79
16 Startup oil for 8 Mu gen in a day KL 20 25

23. Assumptions: Coal Cost = 3000 Rs / Tonne
GCV = 3100 kcal / kg
PLF = 90 % = 4730.4 MU (Yearly)
1 kcal / kWh Saving = 4730.4 x 106 x1 kcal Yearly Saving
Coal Saved = 4730.4 x 106 / 3100 kg
= 1525935.5 kg
= 1526 Tons
1 Kg coal releases 1.25 kg CO2
Hence, CO2 Emission Reduced = 1908 MT CO2
Revenue Saved = 45.78 Lakhs
1 Kcal/KWh
Heat Rate
improvement
1526 MT
Coal (Yearly)
1908 MT CO2
(Yearly)
45.78 Lakhs
(Yearly)

24. 2042
1951 1948 1944
1860
1778 1757
1598
2469
2248 2244 2236
2126
1993
1873
1792
2744
2470
2387 2378
2261
2166
1951 1906
0
500
1000
1500
2000
2500
3000
JSPL - DCPP
Sub-Critical
(135 MW)
JPL - Tamnar
Sub-Critical
(250 MW)
NTPC - Korba
Sub-Critical
(500 MW)
JPL - Tamnar
Sub-Critical
(600 MW)
Adani Power
Mundra
Low Super-Critical
(660 MW)
Tata Mundra
High Super-Critical
(800 MW)
Shandong Zoxian
China
Ultra Super- Critical
(1 0 0 0 M W)
On going research
Advance Ultra
Super-Critical
(800 MW)
Turbine Heat Rate Gross Unit Heat rate Net Heat Rate
Pr – 133 bar
Temp- 540 oC /
540 oC Pr – 147 bar
Temp- 540 oC /
540 oC Pr – 170 bar
Temp- 540 oC /
540 oC Pr – 181 bar
Temp- 540 oC /
540 oC Pr – 247 bar
Temp- 540 oC /
566 oC Pr – 280 bar
Temp- 565 oC /
593 oC Pr – 252 bar
Temp- 605 oC /
605 oC Pr – 310 bar
Temp- 705 oC /
705 oC
Heat Rate of Various Power Stations

25. 31.35
34.81
36.03 36.16
38.03
39.71
44.08
45.12
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
JSPL - DCPP
Sub-Critical
(135 MW)
JPL - Tamnar
Sub-Critical
(250 MW)
NTPC - Korba
Sub-Critical
(500 MW)
JPL - Tamnar
Sub-Critical
(600 MW)
Adani Power
Mundra
Low Super-Critical
(660 MW)
Tata Mundra
High Super-
Critical
(800 MW)
Shandong Zoxian
China
Ultra Super-
Critical
(1 0 0 0 M W)
On going research
Advance Ultra
Super-Critical
(800 MW)
Pr – 133 bar
Temp- 540 oC /
540 oC
Pr – 147 bar
Temp- 540 oC /
540 oC
Pr – 170 bar
Temp- 540 oC /
540 oC
Pr – 181 bar
Temp- 540 oC /
540 oC
Pr – 247 bar
Temp- 540 oC /
566 oC
Pr – 280 bar
Temp- 565 oC /
593 oC
Pr – 252 bar
Temp- 605 oC /
605 oC
Pr – 310 bar
Temp- 705 oC /
705 oC
Efficiency of Various Power Plants

26. Thanks