1. Generation of Eco-friendly Steam in Power Plants
P M V Subbarao
Professor
Mechanical Engineering Department
Generation of Entropy to Generate Most Eligible Steam …..

2. Cost to Benefit Ratio Analysis of Rankine Cycle

3. Heat Rate: An International Standard
The term “heat rate” simply refers to energy conversion efficiency, in terms of
“how much energy must be expended in order to obtain a unit of useful work.”
In a combustion power plant, the fuel is the energy source, and the useful work is the electrical power supplied to the grid.
Because “useful work” is typically defined as the electricity, engineers tend to work with the net plant heat rate (NPHR).
Units: kJ/kW-hr or kCal /kW-hr

4. Method of Calculation Net Plant power output : Pnet in kW
Fuel consumption rate: mfuel kg/hr
Higher heating value or higher calorific value: HHV in kJ/kg

5. Economics of Flow Steam generation

6. Economics of Flow Steam generation
Supercritical Steam Generation
Subcritical Flow Boiling
Pump Exit

7. Natural Circulation Boiler
Dry Steam to Super heaters
Pump Exit
Wet Steam
Hot Water

8. Forced Circulation Boiler
Dry Steam to Super heaters
Pump Exit
Wet Steam
Hot Water
Recirculation Pump

9. Once Through Boiler
Dry Steam to Super heaters
Hot Water
Pump

10. Once Through Subcritical Steam Generator
Once-through tangential fired
Max. continuous rating: 520 kg/s Max.Steam temperature outlet: 540°C Live steam pressure outlet: > 18.3 MPa

11. Super Critical Nuclear Reactor

12. Ranking Cycle using Solar Thermal Energy
Steam at a pressure of 23.5 MPa and 570° C

13. Clues to Generate High Economy and Eco-friendly Steam

14. Constant Pressure Steam Generation Process
Theory of flowing Steam Generation

15. Selection of Steam Generation Pressure in A Rankine Cycle
T C
v, m3/kg

16. Entropy, x=s : A Measure of State of Matter
So (J/K•mol)
H2O(liq) 69.95
H2O(gas) 188.8
For a given substance
S (gaseous state) > S (liquid state) > S (solid state)

17. Entropy and Order of Molecules of Matter
S˚(Br2 liq) < S˚(Br2 gas)
S˚(H2O solid) < S˚(H2O liquid)

18. Entropy, S : Molecular Complexity
Increase in molecular complexity generally leads to increase in S.

19. Standard Molar Entropies

20. Entropy and Temperature
S increases slightly with T
S increases a large amount with phase changes

21. Entropy Change during a Reversible Process
From the definition of the entropy, it is known that Q=TdS during a reversible process.
The total heat transfer during this process is given by Qreversible =  TdS
Therefore, it is useful to consider the T-S diagram for a reversible process involving heat transfer T S
On a T-S diagram, the area under the process curve represents the heat transfer for a reversible process
A reversible adiabatic process

22. Process : h-s Diagram : Mollier Diagram
Enthalpy-entropy diagram, h-s diagram: it is valuable in analyzing steady-flow devices such as turbines, compressors, etc.
Dh: change of enthalpy from energy balance (from the first law of thermodynamics)
Ds: change of entropy from the second law.
A measure of the irreversibilities during an adiabatic process. Ds Dh h s

23. Enthalpy Vs Entropy Diagram

24. Constant Pressure Steam Generation Process
Theory of flowing Steam Generation
Constant Pressure Steam Generation:
A clue to get high temperature with same amount of burnt fuel

25. Steam Generation : Expenditure vs Wastage
Vapour
h mfuel
Liquid +Vapour
Liquid x

26. Steam Generation At High Pressure
x=s

27. Analysis of Steam Generation at Various Pressures
Specific
Pressure
Enthalpy
Entropy
Temp
MPa
kJ/kg
kJ/kg/K C 1
3500
7.79
509.9 2 5
7.06
528.4 3 10
6.755
549.6 4 15
6.582
569 20
6.461
586.7 6 25
6.37
602.9 7 30
6.297
617.7 8 35
6.235
631.3

28. Fuel Savings during Steam Generation
Specific
Temp
Pressure
Enthalpy
Entropy C
MPa
kJ/kg
kJ/kg/K
575 5
3608
7.191 10
3563
6.831
12.5
3540
6.707 15
3516
6.601
17.5
3492
6.507 20
3467
6.422
22.5
3441
6.344 25
3415
6.271 30
3362
6.138 35
3307
6.015

29. Law of Nature Behavior of Vapour at Increasing Pressures
Reversible nature of substance at a given temperature
All these show that the irreversible behavior of a fluid decreased with increasing pressure.

30. Reduction of Wastage

31. Less Fuel for Creation of Same Temperature

32. The Training for High Altitude Trekking

33. Classification of Rankine Cycles

34. Parametric Study of Rankine Cycleh
P max

35. Specific Volume vs Temperature
@15MPa
@35MPa

36. Parametric Study of Rankine Cycle
23.5MPa
22MPa
18MPa
10MPa
6MPa
3MPa h
1MPa
Tmax

38. Reheating : A Means to implement High Live Steam Pressure
Supercritical
593/6210C
593/5930C
565/5930C
565/5650C
538/5650C
Improvement in Efficiency, %
538/5380C