Energy conversion is the process of changing one form of energy into another, a fundamental capability that enables modern civilization to function. It can occur in various ways, from converting the kinetic energy of wind into mechanical power through windmills to transforming solar energy into electrical energy in solar panels. This transformation is essential not just for daily usage but also for harnessing and utilizing natural resources more efficiently. In the context of rural electrification, this process plays a critical role. By converting available local energy resources into electricity, rural communities can access a stable and reliable power supply. This not only improves the quality of life but also supports economic development by powering homes, schools, businesses, and healthcare facilities. Consequently, energy conversion facilitates the broader goal of rural electrification, demonstrating the interconnection between technological innovation and societal advancement.

1. Chapter-2
Thermal Power Plant
Introduction:
• In Steam/Thermal power plants, the heat of combustion of fossil
fuels is utilized by the boilers to raise steam at high pressure and
temperature.
• The steam so produced is used in driving the steam turbines or
sometimes steam engines couples to generators and thus in turn
generating electrical energy.
• Steam power plants may be installed either to generate electrical
energy only or generate electrical energy along with generation
of steam for industrial purposes such as in paper mills, textile
mills, sugar mills, Beer brewing process and food industry etc.

2. Figure: Schematic diagram of a Thermal power plant.

3. Major Components of a Thermal Power Plant
1. Coal and ash handling arrangement
2. Steam generating plant
3. Steam turbine
4. Alternator
5. Feed water and
6. Cooling arrangement
• The whole arrangement can be divided into the following stages for
the sake of simplicity :

4. Cont.…
1. Coal and ash handling plant.
• From the coal storage plant, coal is delivered to the coal handling plant
where it is pulverised (i.e., crushed into small pieces) in order to
promoting rapid combustion process.
• The pulverised coal is fed to the boiler by belt conveyors.
• The coal is burnt in the boiler and the ash produced after the complete
combustion of coal is removed to the ash handling plant and then
delivered to the ash storage plant for disposal.

5. Cont.…
2. Steam generating plant.
• The steam generating plant consists of a boiler for the production of
steam and other auxiliary equipment for the utilisation of flue gases.
i. Boiler
• A boiler (or steam generator) is a closed vessel in which the heat of
combustion of coal inside it is utilised to convert water into steam at
high temperature and pressure.

6. Cont.…
• The flue gases from the boiler make their journey through
superheater, economiser, air pre-heater and are finally exhausted to
atmosphere through the chimney.
• Major types of boilers are: (i) fire tube boiler and (ii) water tube boiler
• Generally water tube boilers are used for electric power stations.
• In this boiler, the water flows inside the tubes and hot gases flow
outside the tube.
• Water tube boiler are classified as
 Vertical tube boiler
 Horizontal tube boiler
 Inclined tube boiler

7. Cont.…
Figure :(a) inclined Water tube (b) vertical water tube
(c) fire tube boilers
(a)
(b) (c)

8. Cont.…
ii. Super heater:
• The function of the super heater is to remove the last trash of moisture
from the saturated steam leaving the boiler tubes and also increases its
temperature above the saturation temperature.
• For this purpose the heat of the combustion gases (Flue gases) from
the furnace (boiler) is utilized.
• Super heated steam is that steam which contains more heat than the
saturated steam at the same pressure.
• The additional heat provide more energy to the turbine hence power
out put is more and hence increase the overall efficiency.

9. Cont.…
Figure : A super heater

10. Cont.…
iii. Economiser.
• An economiser is essentially a feed water heater and derives heat from
the flue gases for this purpose.
• The feed water is fed to the economiser before supplying to the boiler.
• The economiser extracts a part of heat of flue gases to increase the
feed water temperature.
• An increase of about 20% in boiler efficiency is achieved by providing
both economizer and air pre-heaters.
• Economizer alone gives only 10-12% efficiency increase, causes
saving in fuel consumption 5-15 %.

11. Cont.…
iv. Air preheater
• An air preheater increases the temperature of the air supplied for coal
burning by deriving heat from flue gases.
• Air is drawn from the atmosphere by a forced draught fan and is
passed through air preheater before supplying to the boiler furnace.
• The air preheater extracts heat from flue gases and increases the
temperature of air used for coal combustion.

12. Cont.…
3. Steam turbine.
• The dry and superheated steam from the superheater is fed to the
steam turbine through main valve.
• The heat energy of steam when passing over the blades of turbine is
converted into mechanical energy.
• After giving heat energy to the turbine, the steam is exhausted to the
condenser which condenses the exhausted steam by means of cold
water circulation.
.

13. Cont.…
Figure: Steam turbines.

14. Cont.…
4. Alternator.
• The steam turbine is coupled to an alternator. The alternator converts
mechanical energy of turbine into electrical energy.
• The electrical output from the alternator is delivered to the bus bars
through transformer, circuit breakers and isolators,

15. Cont.…
5. Feed water.
• The condensate from the condenser is used as feed water to the boiler.
• The feed water on its way to the boiler is heated by water heaters and
economiser.
• This helps in raising the overall efficiency of the plant.
6. Cooling arrangement.
• In order to improve the efficiency of the plant, the steam exhausted
from the turbine is condensed* by means of a condenser.
• The circulating water takes up the heat of the exhausted steam and
itself becomes hot.

16. Cont.…
• This hot water coming out from the condenser is discharged at a
suitable location down the river.
• In case the availability of water from the source of supply is not
assured throughout the year, cooling towers are used.
• During the scarcity of water in the river, hot water from the condenser
is passed on to the cooling towers where it is cooled.
• The cold water from the cooling tower is reused in the condenser.

17. Steam Cycle:
• Figure 2 shows a simplified version of the major components of a
typical steam plant cycle. This is a simplified version and does not
contain the exact detail that may be found at most power plants.
However, for the purpose of understanding the basic operation of a
power cycle, further detail is not necessary.
• The following are the processes that comprise the cycle:
• 1-2: Saturated steam from the steam generator is expanded in the high
pressure (HP) turbine to provide shaft work out put at constant
entropy.
• 2-3: The moist steam from the exit of the HP turbine is dried and
superheated in the moisture separator reheate r(MSR).

18. Cont.…
• 3-4: Super heated steam from the MSR is expanded in the low
pressure (LP) turbine to provide shaft work output at constant entropy.
• 4-5: Steam exhaust from the turbine is condensed in the condenser in
which heat is transferred to the cooling water under a constant
vacuum condition.
• 5-6: The feed water is compressed as a liquid by the condensate and
feed water pump and the feed water is preheated by the feed water
heaters.
• 6-1: Heat is added to the working fluid in the steam generator under a
constant pressure condition.

19. Cont.…
Figure 2: Typical Steam Plant Cycle

20. Cont.…
• The previous cycle can also be represented on a T-s diagram as was
done with the ideal Carnot cycle. This is shown in Figure 3.
Figure 3: Steam Cycle (Ideal)

21. Fuels and Combustion:
Fuels:
• We use mainly oil and coal, to heat the water to produce the steam to
derive the turbine for huge power generation system (thermal power
generation). These fuels (such as coal, oil and natural gas) are often
referred to as fossil fuels.
• Fuels are majorly classified into
Liquid fuels
Solid fuels
Gas fuels

22. Cont.…
Liquid fuels:
• Liquid fuels like furnace oil and Low Sulphur Heavy Stock (LSHS)
are predominantly used in industrial applications.
• Liquid fuels are
Liquid diesel oil
Furnace oil
LSHS
Kerosene

23. Cont.…
• Sulphur content for the furnace oil is in the order of 2 – 4% because
the main disadvantages of sulphur is the risk of corrosion by sulphuric
acid formed during and after combustion and condensation in cool
parts of the chimney, air preheater and economizer.
• The gross calorific values of the liquid fuel are in the range of 10500
to 11100 Kcal/Kg.
• The ash value is in the range of 0.03 to 0.07%.

24. Cont.…
Solid fuels:
• Solid fuels are nothing but a coal.
• Coal is classified into
 Anthracite (oldest coal from a geological perspective and it is a
hard coal)
 Bituminous
 Lignite (youngest coal from a geological perspective and it is a
soft coal)
• Coal is further classified into
 Semi Anthracite
 Semi Bituminous
 Sub Bituminous

25. Cont.…
• The common coals used in industry are Bituminous and Sub
Bituminous coal.
• The gradation of coal is based on its calorific value and it is shown in
table below.
Grade Calorific Value in
Kcal/Kg.
A Exceeding 6200
B 5600 – 6200
C 4940 – 5600
D 4200 – 4940
E 3360 – 4200
F 2400 – 3360
G 1300 – 2400

26. Cont.…
Gaseous fuels:
• These are most convenient because they require the least
amount of handling and are used in the simplest and most
maintenance free burner system.
• Gas is delivered “on tap” via a distribution network and it is
suited for highly populated area or industrial density.
• Types of gaseous fuels are
Fuels naturally found in nature (natural gas, methane gas
from coal mines)
Fuel gases made from solid fuel (gases derived from coal,
waste and biomass).
Gases made from petroleum (Liquefied Petroleum Gas
[LPG] and Refinery gases).

27. Combustion:
• Combustion refers to the rapid oxidation of fuel accompanied by the
production of heat and light.
• Complete combustion of a fuel is possible only in the presence of an
adequate supply of oxygen (O2).
• Oxygen is one of the common elements on earth. That is 20.9% of
oxygen is present in the air.
• Rapid fuel oxidation results in large amount of heat.
• Solid or liquid fuels must be changed to gas before they will burn. For
this the heat is required to change the state (solid or liquid to gas).

28. Cont.…
• Fuel gas will burn in their normal state if enough air is present.
• . The objective of good combustion is to release all of the heat in fuel.
This is accomplished by controlling three T’s of Combustion which
are
Temperature – high enough to ignite
Turbulence – intimate mixing of the fuel and oxygen
Time – sufficient for complete combustion.

29. Gas Turbine:
• A gas turbine, also called a combustion turbine, is a type of internal
combustion engine.
• It has an upstream rotating compressor coupled to a downstream
turbine, and a combustion chamber in between and it is shown in
Figure below.

30. Cont...
• The basic operation of the gas turbine is similar to that of the steam
power plant except that air is used instead of water.
• Fresh atmospheric air flows through a compressor that brings it to
higher pressure.
• Energy is then added by spraying fuel into the air and igniting it so the
combustion generates a high-temperature flow.
• This high-temperature high-pressure gas enters a turbine, where it
expands down to the exhaust pressure, producing a shaft work
output in the process.

31. Cont..
• The turbine shaft work is used to drive the compressor and other
devices such as an electric generator that may be coupled to the shaft.
• The energy that is not used for shaft work comes out in the exhaust
gases.
• Gas turbines are used to power aircraft, trains, ships, electrical
generators, or even tanks.

32. Selection of site for thermal power plant
Nearness to the load centre:
• The power plant should be as near as possible to the load centre to the centre
of load .
• So that the transmission cost and losses are minimum.
Water resources:
• For the construction and operating of power plant large volumes of water
are required for the following reasons. To raise the steam in boiler.
 To raise the steam in boiler
 For cooling purpose such as in condensers
 As a carrying medium such as disposal of ash.

33. Cont.…
Availability of Coal:
• Huge amount of coal is required for raising the steam.
• So, for power generation purposes, the steam power plants should be located
near the coal mines to avoid the transport of coal & ash.
Land Requirement:
• The land is required not only for setting up the plant but for other purposes
also such as staff colony, coal storage, ash disposal etc.
Transportation Facilities:
• The facilities must be available for transportation of heavy equipment
and fuels e.g near railway station.
Labour supplies:
• Skilled and unskilled laborers should be available at reasonable rates near
the site of the plant.

34. Advantages And Disadvantages Of Thermal Power Plant
Advantages:
• Less initial cost as compared to other generating stations.
• It requires less land as compared to hydro power plant.
• The fuel (i.e. coal) is cheaper.
• The cost of generation is lesser than that of diesel power
plants.
Disadvantages:
• It pollutes the atmosphere due to the production of large
amount of smoke. This is one of the causes of global
warming.
• The overall efficiency of a thermal power station is low
(less than 30%).
• Requires long time for errection and put into action.
• Requirement of water in huge quantity.

35. Thank you !