thermal powerplant

1. Thermal Power plants
BY :-
SAI KUMAR,
VARUN,
(JNTUK).

2. INTRODUCTION
• In India 65% of total power is generated by the Thermal Power
Stations.
• In thermal generating stations coal, oil, natural gas are employed as
primary sources of energy .
• A thermal power station basically work on the rankine cycle.
• Thermal power plant convert the heat energy of coal into electrical
energy.
• Coal is burnt in a boiler which converts water into steam.
• The expansion of steam in turbine produces mechanical power which
drives the alternator coupled to the turbine.

3. SOURCES
• COAL SOURCE
• WATER SOURCE
• OIL SOURCE
• GAS SOURCE

4. DEFINITION
A generating station which converts heat
energy of coal combustion into electrical energy
is known as thermal power station.

5. OPERATION MECHANISM
• The coal is brought and crushed to powder, This is feed to boiler for producing heat .
• In Boiler the water is converted to steam.
• In super heater the moisture content is removed from the steam and that steam is called super heated steam.
• The superheated steam rotates the shaft of the High pressure turbine.
• The exhausted steam is sent to preheater and the steam then rotates the intermediate pressure (IP) turbine.
• The steam from the IP Turbine is then feed to low pressure turbine.
• The turbine shaft is connected to the Generator, which produces electric Power.
• The power generated is then transmitted .

6. GENERAL LAYOUT OF THERMAL POWER STATION

7. Schematic arrangement of steam power station

8. COAL HANDLING PLANT
Raw coal wagon – Coal is brought to the site
through a wagon as per the requirement.
Wagon tippler – The coal is unloaded from
the wagon and is transported to crusher
and for storage place through conveyor.
Junction tower - JTs are used where the conveyor
has any angular deviation.
Primary crusher – The raw coal is crushed into fine pieces of 45mm
grit. Primary crusher is also called Rotatory breaker since the coal
is crushed by rotating plate.
The stone and
unwanted coal
are rejected

9. Secondary crusher – The fine pieces
of coal is crushed into powder . (25
mm grit).
Junction Tower
Mill Bunker – The 25 mm grit coal is
crushed into very fine powder for feeding
the boiler . We will have a spare bunker for
each boiler.
Boiler
Stack & Re claimer – It
is used to store the
powdered coal for
emergency purpose.
Atmospheric air
–Through FD
fan

10. PULVERIZING PLANT
• In modern thermal power plant , coal is pulverized
• ground to dust like size and carried to the furnace in a stream of hot air.
• Pulverizing is a means of exposing a large surface area to the action of
oxygen and consequently helping combustion.
• Pulverizing mills are further classified as:
1. Contact mill
2. Ball mill
3. Impact mill

11. BOILER
• A boiler or steam generator is a closed vessel to
which water under pressure, is converted into steam.
• It is one of the major components of a thermal power
plant.
• Always designed to absorb maximum amount of heat
released in the process of combustion.

12. SUPER HEATER & RE HEATER
MOST OF THE MODERN BOILERS ARE HAVING SUPER HEATER AND RE HEATER ARRANGEMENT.
• Super heater is a component of a steam-generating
unit in which steam, after it has left
the boiler drum, is heated above its saturation
temperature.
• The super heater may consist of one or more
stages of tube banks arranged to effectively
transfer heat from the products of combustion.
• Super heaters are classified as convection ,
radiant or combination of these.

13. Re heater :
Some of the heat of superheated steam is used to rotate the turbine where it loses
some of its energy. Re heater is also steam boiler component in which heat is added
to this intermediate-pressure steam, which has given up some of its energy in
expansion through the high-pressure turbine. The steam after reheating is used to
rotate the second steam turbine where the heat is converted to mechanical energy.
This mechanical energy is used to run the alternator, which is coupled to turbine ,
there by generating electrical energy.

14. DRAFT SYSTEM
• The circulation of air is caused by a
difference in pressure, known as
Draft.
• Draft is a differential pressure b/w
atmosphere and inside the boiler.
• It is necessary to cause the flow of
gases through boiler setting It may be
–
1.Natural draft
2.Mechanical draft

15. STEAM TURBINE
• A steam turbine converts heat energy of steam into mechanical energy and
drives the generator.
• It uses the principle that steam when issuing from a small opening attains a
high velocity.
• This velocity attained during expansion depends on the initial and final heat
content of the steam.
• This difference b/w initial and final heat content represents the heat energy
converted into kinetic energy.
• These are of two types :-
1. Impulse turbine
2. Reaction turbine

16. ALTERNATOR
• Turbine and alternator are mechanical
coupled with each other.
• Alternator convert mechanical energy
of turbine into electrical energy.
• The electrical output from the
alternator is delivered to the bus bar
through transformer.

17. CONDENSER
• Which condenses the steam at the exhaust of turbine.
• It creates a very low pressure at the exhaust of turbine, this helps
in converting heat energy of steam into mechanical energy in the
prime mover.
• The condensed steam can be used as feed water to the boiler.

18. GENERATOR
• The Synchronus Generator is used to generate power by connecting the
shaft of the Turbine to the shaft of the generator which create the
magnetic flux producing Emf.
• The generated voltage will generally 33 KV to 11 KV max.
• the generated Voltage is stepped up by connecting Step up transformer
and is also used for auxilliary purpose.

19. COOLING TOWER
• Remove heat from the water
discharged from the
condenser so that the water
can be discharged to the river
or re circulated and reused.
• Air can be circulated in the
cooling towers through
natural draft and mechanical
draft.

20. ECONOMIZER
• Flue gases coming out of the boiler
carry lot of heat.
• An economizer extracts a part of this
heat from flue gases and uses it for
heating feed water.
• This use of economizer results in
saving coal consumption and higher
boiler efficiency

21. AIR PREHEATER
• An air pre heater increases the temperature of
air supplied for coal burning
• And it driven from the flue gases.
• Air is drown from the atmosphere by the force of
draft fan.
• Air preheaters may be of three types
1. Plate type
2. Tubular type
3. Regenerative type

22. ASH HANDLING PLANT
• The percentage of ash in coal varies from 5% in
good quality coal to about 40% in poor quality coal
Power plants generally use poor quality of coal .
• thus amount of ash produced by it is pretty large .
• A modern 2000MW plant produces about 5000 tons
of ash daily.
• The stations use some conveyor arrangement to
carry ash to dump sites directly or for carrying and
loading it to trucks and wagons which transport it
to the site of disposal

23. UTILISATION OF SECONDARY RAW MATERIAL (ASH)
• Construction of embankments and fills.
• Construction of road in sub-base.
• Manufacture of cement.
• Manufacture of bricks/blocks.
• Agriculture as soil amendment/source of essential plant nutrients.

24. Advantages
• The fuel used is quite cheap.
• Less initial cost as compared to other generating plants.
• It can be installed at any place irrespective of the existence of coal.
• The coal can be easily transported to the site
• It require less space as compared to Hydro power plants.
• Cost of generation is less than that of diesel power plants.

25. DISADVANTAGES
• It pollutes the atmosphere due to production of large amount of smoke and
fumes.
• It is costlier in running cost as compared to Hydro electric plants.
• Maintenance cost is more

26. REFERENCES:-
TEXTBOOKS:
DR. KVSG MURALI KRISHNA,
WWW.GOOGLE.COM
WWW.SLIDESHARE.NET

27. Thank
You