thermal power or steam power plant

1. Thermal Power Plant
Prepared By:
Vivek Pathak

2. INTRODUCTION
Talking of a thermal power, a number of major
parameters need to be considered. Firstly, selecting
a suitable site for a thermal pant is of utmost
importance.
 The thermal plant consumes huge amount of fuel
principally coal.
 It is estimated that for every megawatt produced, a
plant needs more than 10,000 tons of coal.


3. Arrangement must exist to bring the coal from mines and
store the coal.
 Secondly, in the Thermal power plant layout, there must be
provision to dispose of large quantities of ash generated.
 It is estimated that for storage of coal, ash disposal building
of the plant itself and residential space for workers etc you
would need approximately 3 acres of land for every
megawatt generated.
 Lastly you need huge quantities of water to run the plant. A
perennial water source like a river nearby is needed to run a
thermal power plant.


4. INTRODUCTORY OVERVIEW
A thermal power station is a power plant in which
the prime mover is steam driven.
 Water is heated, turns into steam and spins a
steam turbine which drives an electrical generator.
 After it passes through the turbine, the steam is
condensed in a condenser and recycled to where it
was heated.


5. 
The greatest variation in the design of thermal power
stations is due to the different fuel sources.

6. Energy Conversion Process in Thermal
Power Plants
Fuel
Chemical
Energy
Chemical Energy is
Converted into Thermal
Energy by Combustion
In Boiler
Thermal
Energy
Thermal Energy is
Converted into
Mechanical Energy
In Turbine
Mechanical
Energy
Electrical
Energy
Mechanical Energy is
Converted into
Electrical Energy
In Generator

7. Energy Conversion . . .




Fuel, Air and water produce steam in the boiler by
combustion
Steam of high temperature and pressure is
expended from high pressure to low pressure in the
turbine
Thermal energy is converted into kinetic energy and
finally mechanical energy
This mechanical energy derives the generator to
produce electricity

8. Thermal Power Plant can work in two
Manners
1.
2.
Production of electricity
Production of electricity with production of
steam for the use in industry e.g. paper
mills, textile mills, sugar mills, refineries

9. Processing of Power Plant
Boiler
Water
Steam
Grid
Turbine
Fuel
Generator
Exhaust Steam
Waste Gases

10. Efficiency
Efficiency = Heat Equivalent of Electrical output / Heat of Combustion
Normally η = 29%
Losses:
1.
Boiler House Losses:
a. To Dry Fuel Gases
b. To moisture in gases
c. To ash and unburnt carbon
d. To radiation and leakage
e. Unknown losses
TOTAL

5%
5%
1%
2.5%
2.5%
16%

11. Efficiency . . .
Turbine Losses:
a. Heat rejection to Condenser
54%
3. Alternator or Generator Loss 1%
TOTAL
55%
Grand Total
71%
So Efficiency = (100% - Losses)
= 100% - 71% = 29%
2.

12. Merits of Thermal Power Plant






Fuel is cheaper*
Less space is required
The initial cost is less
Plant can be located near the load centre
Turbine can work at 25% overload continuously
A portion of steam can be used in various industries

13. Demerits of Steam Power Plant






Maintenance and operating costs are high
Pollution of atmosphere is one of the major
problems
Water is required in huge quantity
Handling of coal and disposal of ash are
difficult tasks
It requires long time for installation
Efficiency falls quickly below 75%

14. Site Selection







Availability of Coal (Fuel)
Proper arrangement for ash disposal
Nature of the land
Location from load centre
Availability of water
Transport facilities
Availability of labor

15. Main Circuits of Thermal Power Plant




Coal and Ash Circuit
Air and Gas circuit
Feed Water and Steam circuit
Cooling Water circuit

16. Coal and Ash Circuit


Coal from the storage is fed to the boiler
through coal handling equipment for the
generation of steam.
Ash produced due to combustion of coal is
removed to ash storage through ashhandling system

17. Air and Gas Circuit





Air is supplied to the combustion chamber of the
boiler either through forced draught or induced
draught fan or by using both.
The dust from the air is removed before supplying to
the combustion chamber.
The exhaust gases carrying sufficient quantity of
heat and ash are passed through the air-heater.
Here the exhaust heat of the gases is given to the air
then it is passed through the dust collectors where
most of the dust is removed before exhausting the
gases to the atmosphere

18. Feed Water and Steam Circuit





The steam generated in the boiler is fed to the steam prime
mover to develop the power
The steam coming out of the prime mover is condensed in the
condenser and then fed to the boiler with the help of pump
The condensate is heated in the feed-heaters using the steam
tapped from different points of the turbine
The feed water supplied from external source is passed through
the purifying plant to reduce to reduce dissolve salts to an
acceptable level
This purification is necessary to avoid the scaling of the boiler
tubes

19. Cooling Water Circuit


The quantity of cooling water required to
condense the steam is considerably high and
it is taken from a lake, river or sea
. The water is pumped in by means of pumps
and the hot water after condensing the steam
is cooled before sending back into the pond
by means of cooling towers

20. Major Parts of Steam Power Plant
1. Boilers
3. Turbine
5. Economizer
7. Induced Draft Fan
9. Chimney
11. Ash Handling Plant
13. Alternator
15. Pumps
2. Superheater
4. Condenser
6. Air preheater
8. Forced Draft Fan
10. Coal Handling Plant
12. Cooling Tower
14. Evaporator

21. 1. Boiler
Purpose: To produce steam under pressure
Types:
1.
Fire Tube Boiler: Hot gases of combustion are
inside the tubes and the tubes are surrounded by
water
2.
Water Tube Boiler: Water is inside the tube and
hot gases are outside the tube
One of these are used according to the requirements

23. Fire Tube Boiler

24. Water Tube Boiler

25. Superheater
Device used to remove the traces of moisture from saturated
steam leaving boiler tubes.

It also increase the temperature above saturation temperature
Classes:
1.
Radiant Superheater: Located in the furnace between the
furnace water walls and absorbs heat from the burning fuel
through radiation
2.
Convection Superheater: Located well back in boiler tube
bank. It receives its heat from flue gases through convection.


26. Economizer


It absorbs heat from outgoing flue gases and
used for raising the temperature of feed
water coming from condenser
Economizer raises efficiency of boiler by 10 12 % thus 5 – 15 % of fuel consumption is
saved

27. Air Preheater


Air preheater is used to recover heat from
flue gases since entire heat can’t be
extracted by economizer
Boiler Efficiency is increased by 1% if the
avg. air temp. is increased by 20 C

29. Steam Turbines

1.
2.
There are two types of steam turbines
Impulse type: Steam expands completely in
the stationary nozzles, the pressure over
the moving blades remains constant.
Reaction Type: Steam is expanded both in
fixed blades (nozzles) and moving blades.

32. Coal Handling
1.

2.

Coal shouldn’t be exposed to air
It pollutes the air and releases poisonous gases
like carbon monoxide
The coal from the heaps is moved into the plant by
means of long conveyors that are electrically
operated
There are many different types of conveyors and
coal-handling devices like screwing conveyors,
bucket elevators, grabbing bucket conveyors etc.

35. Coal Crusher


Before the coal is sent to the plant it has to
be ensured that the coal is of uniform size so
it is passed through the crushers
Rotary crushers are very commonly used for
this purpose as they can provide a
continuous flow of coal to the pulverizer

37. Coal Crusher . . .

38. Pulverizer



Are used to smash materials into tiny
granular.
Most commonly used pulverizer is the Boul
Mill
The arrangement consists of 2 stationary
rollers and a power driven baul in which
pulverization takes place as the coal passes
through the sides of the rollers and the baul

41. THERMAL POWER PLANT
LAYOUT

43. Installed Plant Capacity Of Thermal
Power Plant In India

47. Installed Plant Capacity Of Thermal
Power Plant In World

48. Rank
Station
Country
Location
Capacity (MW)
Ref
1
Taichung Power Plant
Taiwan
24°12′46″N 120°28′52″E
5,500
[23]
2
Tuoketuo Power Station
China
40°11′49″N 111°21′52″E
5,400
[24][25][26]
3
Bełchatów Power Station
Poland
51°15′59″N 19°19′50″E
5,354
[27][28][29]
4=
Guodian Beilun Power
Station
China
29°56′37″N 121°48′57″E
5,000
[30]
4=
Waigaoqiao Power Station China
31°21′21″N 121°35′54″E
5,000
[31][32]
4=
Guohoa Taishan Power
Station
China
21°52′00″N 112°55′22″E
5,000
[33]
4=
Jiaxing Power Station (zh)
China
30°37′46″N 121°8′49″E
5,000
[34]