This presentation talks about the general concepts about a thermal power plant. I starts by explaining the basic forms of energy. under this thermal power plant the working principles of steam, gas turbine and combined cycle processes are presented again this presentation is a guideline not a full and complete document.

1. CHAPTER TWO
THERMAL POWER PLANTS
By Mesfin Megra

2. OUTLINE
•Introduction
•Steam power plant
•Fuels and combustions
•Gas turbine and
•Combined cycle and operating practices
1/28/2018 2

3. INTRODUCTION
➢ According to the principle of conservation of energy in
any closed system the total amount of energy remains
constant.
➢ But energy may change from one form to another but the
total amount in a closed system remains constant.
❖ Therefore what are the main forms of energy?
1/28/2018 3

4. CONT.…
➢ There are seven major forms of energy
a) Potential energy d) Electrical energy
b) kinetic energy e) Nuclear (mass) energy
c) chemical energy f) Heat energy g) Radiant Energy
➢Question, What are the six ultimate sources of energy?1/28/2018 4

5. ➢There are six ultimate sources of energy
1.The sun
2.Geothermal energy from cooling, chemical reaction and
the radioactive decay inside the earth.
3.The motion and gravitational potential of the sun, moon
and earth
1/28/2018 5
Cont…

6. 4. Nuclear reaction on the earth
5.Chemical reaction from mineral sources
6.Fossil fuel (petroleum products and gases)
➢Question, What are the two major categories for sources of
energy? 1/28/2018 6
Cont…

7. ➢Energy sources are mainly categorized in to two big classes
1. Renewable energy is the energy obtained from regenerative or virtually
in exhaustible sources of energy occurring in the natural environment like
solar, wind, etc (non-conventional sources of energy)
2. Non-renewable energy is the energy obtained from static stores of energy
that remain bound unless released by human interaction. Example coal, oil,
natural gas(they are called finite or conventional energy sources)1/28/2018 7
Cont…

8. Cont…
➢The sun can be used in to ways these are directly or indirectly
1.Direct form of solar energy : in such kinds of solar energy
the sun is used directly to produce the energy required
2.Indirect forms of solar energy: in this form the sun is used to
create other forms of energy 1/28/2018 8

9. Cont…
Solar
energy
Solar
thermal
Flat plate
collector
concentrators
lenses
Photovoltaic
cells
Stand alone
Isolated power
pants
Grid connected
1. Direct form of solar energy
1/28/2018 9

10. Cont… Sun
Wind
energy
Uneven heating
of the earth
surface
Biomass
energy
Photosynthesis
process
Hydropower
energy
Hydrological
cycle
2. Indirect forms of solar energy
1/28/2018 10

11. ➢A power plant is assembly of systems or subsystems to
generate electricity,
➢A power plant may be defined as a machine or assembly of
equipment that generates and delivers a flow of mechanical
or electrical energy.
1/28/2018 11
Cont…

12. Cont…
1/28/2018 12
Power plants
conventional
Steam engine power plant
Steam turbine power plant
Diesel power plant
Gas turbine power plant
Nuclear power plant
Non-conventional
Thermoelectric generator
Fuel-cell power plant
PV power plant
Biogas, biomass power plant
Geothermal power plant
Wind power plant
Ocean power plant

13. ➢The main equipment for the generation of electric power is
generator. When coupling it to a prime mover runs the
generator, the electricity is generated.
➢The type of prime move determines, the type of power
plants.
1/28/2018 13
Cont…

14. ➢Those power plants which convert heat into electric energy
are called THERMAL POWER PLANTS.
➢Steam Power Plant, Diesel Power Plant, Gas Turbine Power
Plant and Nuclear Power Plants are thermal power plant
1/28/2018 14
Thermal power plants

15. ➢Steam is an important medium of producing mechanical
energy.
➢Steam has the advantage that, it can be raised from water
which is available in abundance, it does not react much with
the materials of the equipment of power plant and is stable
at the temperature required in the plant. 1/28/2018 15
steam power plants

16. ➢Steam is used to drive steam engines, steam turbines etc.
➢Steam power station is most suitable where coal is available
in abundance.
➢Thermal electrical power generation is one of the major
method. 1/28/2018 16
Cont…

17. Cont…
1/28/2018 17

18. ➢A steam power plant must have the following equipment:
➢A furnace to burn the fuel.
➢Steam generator or boiler containing water. Heat generated in the furnace
is utilized to convert water in steam.
➢Main power unit such as an engine or turbine to use the heat energy of
steam and perform work.
➢Piping system to convey steam and water. 1/28/2018 18
Cont…

19. ➢A steam power plant using steam as working substance
works basically on Rankine cycle.
➢Reading assignment Rankine cycle
➢Steam is generated in a boiler, expanded in the prime
mover and condensed in the condenser and fed into the boiler
again.
1/28/2018 19
Cont…

20. ➢Coal received in coal storage yard of power station is
transferred in to the furnace by coal handling unit.
➢Heat produced due to burning of coal is utilized in
converting water contained in boiler drum into steam at
suitable pressure
•and temperature. 1/28/2018 20
Working principle of steam power plants

21. ➢The steam generated is passed through the super-heater.
➢Superheated steam then flows through the turbine.
➢After doing work in the turbine the pressure of steam is
reduced.
➢Steam leaving the turbine passes through the condenser1/28/2018 21
Cont…

22. ➢Steam pressure in the condenser depends upon flow rate
and temperature of cooling water and on effectiveness of air
removal equipment.
➢Water circulating through the condenser may be taken from
the various sources such as river, lake or sea.
1/28/2018 22
Cont…

23. ➢Air taken from the atmosphere is first passed through the air pre-
heater, where it is heated by flue gases.
➢The hot air then passes through the furnace.
➢The flue gases after passing over boiler and super-heater tubes,
flow through the dust collector and then through economizer and
finally they are exhausted to the atmosphere through the chimney.1/28/2018 23
Cont…

24. QUIZ 10% TIME 5 MIN LEFT
1. With the help of a diagram explain the
working principle of a steam power plant. Also
draw the T-S diagram for the Rankine cycle and
the four process associated with it.
1/28/2018 24

25. ➢The gas turbine obtains its power by utilizing the energy of
burnt gases and air.
➢It is at high temperature and pressure by expanding through
the several ring of fixed and moving blades.
➢It thus resembles a steam turbine.
1/28/2018 25
Gas Turbines power plant

26. ➢Gas turbines are used by a very wide range of services most
notably for powering aircraft of all types.
➢But also it can be used in industrial plants for driving
mechanical equipment such as pumps, compressors and small
generator in electrical utilities.
1/28/2018 26
Con….

27. ➢Gas turbines for producing electric power for peak loads as
well as intermediate and some base load.
➢There is also growing interest in using gas turbines in
combined combine cycle plants.
➢Combined cycle plants use both steam and gas turbines.
1/28/2018 27
Con….

28. ➢A simple gas turbine cycle consists of
➢a compressor: is used to increase the pressure of the air
➢a combustion chamber: used to increase the air temperature
➢a turbine:
1/28/2018 28
Gas Turbine cycles

29. ➢The gas turbine power plants which are used in electric
power industry are classified into two groups as per the cycle
of operation.
➢Open cycle gas turbine and
➢closed cycle gas turbine
1/28/2018 29
Con….

30. Open Cycle Gas Turbine power plant
1/28/2018 30

31. ➢A simple open cycle gas turbine consists of a compressor,
combustion chamber and a turbine.
➢The compressor takes in ambient air and raises its pressure.
➢Heat is added to the air in combustion chamber by burning
the fuel and raises its temperature.
1/28/2018 31
Con….

32. ➢The heated gases coming out of combustion chamber are
then passed to the turbine where it expands doing mechanical
work.
➢Part of the power developed by the turbine is utilized in
driving the compressor & other accessories, remaining is used
for power generation. 1/28/2018 32
Con….

33. ➢Since ambient air enters into the compressor and gases
coming out of turbine are exhausted into the atmosphere, the
working medium must be replaced continuously.
➢This type of cycle is known as open cycle gas turbine plant.
➢is mainly used in majority of gas turbine power plants
1/28/2018 33
Con….

34. Closed Cycle Gas Turbine Power Plant
1/28/2018 34

35. ➢In closed cycle gas turbine plant, the working fluid (air or
any other suitable gas) coming out from compressor is heated
in a heater by an external source at constant pressure.
➢The high temperature and high-pressure air coming out from
•the external heater is passed through the gas turbine.
1/28/2018 35
Con….

36. ➢The fluid coming out from the turbine is cooled to its original
temperature in the cooler using external cooling source before
passing to the compressor.
➢The working fluid is continuously used in the system without its
change of phase.
1/28/2018 36
Con….

37. ➢The ideal cycle for gas turbine is Brayton Cycle or Joule
Cycle.
➢This cycle is of the closed type using a perfect gas with
constant specific heats as a working fluid.
➢This cycle consists of the following processes:
1/28/2018 37
Gas Turbine Efficiency

38. Con….
1/28/2018 38

39. ➢The cold air at 3 is fed to the inlet of the compressor where
it is compressed along 3-4. (Adiabatic compression)
➢Then fed to the combustion chamber where it is heated at
constant pressure along 4-1. (Isobaric process)
➢The hot air enters the turbine at 1 and expands
adiabatically along 1-2. (Adiabatic expansion) 1/28/2018 39
Con….

40. ➢Then cooled at constant pressure along 2-3. (Isobaric
process)
➢Thus the efficiency of joules cycle is given by:
η =
𝑊𝑜𝑟𝑘 𝑑𝑜𝑛𝑒
𝐻𝑒𝑎𝑡 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑
𝑤𝑜𝑟𝑘 𝑑𝑜𝑛𝑒 = ℎ𝑒𝑎𝑡 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 − ℎ𝑒𝑎𝑡 𝑟𝑒𝑗𝑒𝑐𝑡𝑒𝑑1/28/2018 40
Con….

41. ➢It has been found that a considerable amount of heat energy
goes as a waste with the exhaust of the gas turbine.
➢This energy must be utilized.
➢The complete use of the energy available to a system is
called the total energy approach.
1/28/2018 41
Combined cycle power plants

42. Con….
1/28/2018 42

43. END OF CHAPTER TWO
1/28/2018 43