thermal power plant

1. By:- SRIKANTA SINHA
10371A0368

2. Introduction to thermal power station
 About KTPS
 Principle of operation
 Coal to steam process
 Steam to mechanical power
 Mechanical power to electrical power
 Electrical power transmission

3. About “KTPS”
 Kothagudem Thermal Power Station
 First major thermal power station set up in Andhra
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Pradesh State Electricity Board
Basically coal fired thermal power generating station
Total installed capacity : 1720W
KTPS A Station : Unit 1,2,3&4 of 60MW capacity
KTPS B Station : Unit 5&6 of 120 MW capacity
KTPS C Station : Unit 7&8 of 120 MW capacity
KTPS stage V consists of Unit 9&10 of 250 MW
KTPS stage VI produces 500MW

4. Coal fired power station
Layout of coal fired power station

5. Schematic layout of thermal power station

6. Principle of operation
The three “R” cycles
Rankine Cycle
Reheat Cycle
Regenerative Cycle

7. RANKINE CYCLE
Schematic layout and Ts diagram for Rankine cycle

8. REHEAT CYCLE
Ts diagram for Reheat Rankine Cycle

9. REGENERATIVE CYCLE
Ts diagram for Regenerative Rankine Cycle

10. Coal to steam process
 Coal from the coal wagons in unloaded in the coal
handling plant.
 The coal is transported up to the raw coal bunkers
with the help of belt conveyors.
 Coal is then transported to mills through feeders
where the coals are pulverized to powder form. This
crushed coal is taken away to the furnace through coal
pipes with the help of hot and cold air mixtures from
PA fan.
 PA fan takes atmospheric air, a part of which is sent to
air-pre heater for heating while a part goes directly to
the mill for temperature control

11.  Atmospheric air from FD fan is heated in the air heaters
and sent to the furnace as combustion air.
 Water from the boiler feed pump passes through the
economizer and reached the boiler drum. Then passes
through the down comers goes to bottom ring header.
Water from the bottom ring header is divided to all four
sides of a furnace.
 Due to heat and density difference the water raises up in
the furnace. This steam and water mixed is taken up to the
boiler drum where the steam is separated from water.
 Water follows the same path while the steam is sent to the
super heaters for super heating. The super heaters are
located inside the furnace and the steam is superheated
and sent to the turbine.

12.  Flue gases from the furnace is extracted by induced draft
fan, which maintains balance in the furnace with the forced
draft fan.
 These flue gases emit their heat energy to various super heaters
in three pent houses and finally passes through air pre heaters
and goes to electro precipitator where the ash particles are
extracted.
 Electrostatic precipitators consists of metal plates which are
electrically charged. Ash particles are attracted on to these
plates so that they do not pass though the chimney to pollute
the atmosphere.
 Regular mechanical hammer blows cause the accumulation of
ash to fall to the bottom of the precipitator, where they are
collected in a hopper for the disposal. The ash is mixed with
water to form slurry and is pumped to ash pond

13. Steam to mechanical power
 A steam pipe conveys the steam to the turbine through
the stop valve and control valve that automatically
regulates the supply of steam to the turbine.
 Steam from the control valve enters the high pressure
cylinder of the turbine, where it passes through a ring of
stationary blades fixed to the cylinder wall. These acts as
nozzles and direct the steam into a second ring of moving
blades mounted on a disc secured to a turbine shaft.
 This second ring turns the shaft as a result of the force of
the steam. The stationary and the moving blades
together constitute a stages of turbine.
 The steam passes through each stage in turn until it
reaches the end of HP cylinder where heat energy is
changed into mechanical energy.

14.  The steam leaving the HP cylinder goes back to the boiler for
reheating and enters into the intermediate pressure cylinder
through HRH lines. Hence it passes through another series of
stationary and moving blades
.
 Finally steam is taken to the low pressure cylinders, each of
which is enters at the center for flowing outwards in the
opposite direction through the rows of turbine bladed
arrangement is known as double flow to the extremities of
the cylinder.
 As the steam gives its heat energy to drive the turbine, its
temperature and pressure falls and it expands.
 So because of this expansion the blades are much larger and
longer towards the low pressure ends of the turbine.

15. Mechanical power to electrical power
 Basic principle of electrical power generation is from
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Faraday’s laws. It states that “ when a conductor rotates in
magnetic field, the emf will be induced in a conductor
and is proportional to the rate of change of flux lines cut
by the conductor and capacity of the magnetic field.”
Magnetic field is obtained from a separate system called
the Excitation system.
Excitation system is classified into two types ;
Static Excitation
Brush-less Excitation
The speed of the turbine is determined by the electrical
system used in the country i.e. 50 Hz.
Speed of the turbine : 3000 rpm

16. Electrical power transmission
 Electrical power is usually produced in the stator
windings of large modern generators at about 15.75 kV
and is fed through terminal connections to one side of
a generator transformer that set up the voltage to
220kV and transmitted.
 Now –a-days power transmission is carried out even
with a high voltage of 400kV.
 Increase of transmission voltage reduces the line losses
and increases the efficiency of the overall system.

17. Major components of power station
 MILLS
 BOILER
 FANS
 DEAERATOR
 ESP (ELECTROSTATIC PRECIPITATORS)
 STEAM TURBINES
 CONDENSER
 PUMPS

18. MILLS

19. Coal mill principle
Coal of less than 50mm size is fed by feeder through central feed pipe into
the revolving bowl of the bowl mill. Centrifugal force feeds the coal
uniformly between the bull ring and independently rotating spring loaded
rolls to travel through the outer periphery of the bowl. The springs, which
load the rolls, impart the pressure necessary for grinding. The partially
pulverized coal continues to move up over the edge of the bowl due to
centrifugal force
Coal mill feature
1. Reject Removal :Any tramp iron or dense foreign material in the raw coal feeder,
which is difficult to grind, if carried over to the top of the bowl is dropped out
through the air stream to the lower part of the mill side housing. The mill rejects
can be intermittently taken out from the pyrite hopper, first by closing the inner
gate and opening the outer gate of the hopper.
2. Temperature Control: The Bowl mill can be isolated completely for maintenance
work by closing the Hot air shut off gates, cold air shut off gates, pulverized
discharge valves and seal air valve.
3. Mill air flow :Mill should be operated at the design airflow at all loads. Operating
at higher airflow will cause excess wear and fineness will be decreased. If mill is
operated at lower airflow, it may result into coal rejects & excess fineness.

20. BOILERS

21. BOILER
 Definition of Boiler
Steam boiler or simply a boiler is basically a closed vessel into
which water is heated until the water is converted into steam at
required pressure. This is most basic definition of boiler.
 Working Principle of Boiler
The basic working principle of boiler is very simple and easy
to understand. The boiler is essentially a closed vessel inside
which water is stored. Fuel (generally coal) is bunt in a furnace
and hot gasses are produced. These hot gasses come in contact
with water vessel where the heat of these hot gases transfer to
the water and consequently steam is produced in the boiler.
 Then this steam is piped to the turbine of thermal power plant.
There are many different types of boiler utilized for different
purposes like running a production unit, sanitizing some area,
sterilizing equipment, to warm up the surroundings etc.

22. Types of Boiler
There are mainly two types of boiler –
Water tube boiler and fire tube boiler
In water tube boiler the water is heated inside tubes and
hot gasses surround these tubes.
The fire tube boiler consists of numbers of tubes through
which hot gasses are passed. These hot gas tubes are
immersed into water, in a closed vessel. Actually in fire
tube boiler one closed vessel or shell contains water,
through which hot tubes are passed. These fire tubes or hot
gas tubes heated up the water and convert the water into
steam and the steam remains in same vessel. As the water
and steam both are in same vessel a fire tube boiler cannot
produce steam at very high pressure. Generally it can
produce maximum 17.5 kg/cm2 and with a capacity of 9
Metric Ton of steam per hour.

23. Schematic diagram of boiler

24. FANS
 FANS FOR POWER PLANT
Supply air for combustion in the furnace and for evacuation of
the flue gases formed from the combustion.
Maintain Balanced Draft inside the furnace.
Supply air for cooling of equipments working in hot zones.
Supply air for sealing of gates, feeders & mills bearings etc.
Air used for combustion is divided into 2 parts:
1.PRIMARY AIR
Portion of total air sent through mills to the furnace. This air
dries the pulverized coal and transport it to the furnace for
combustion.
2.SECONDARY AIR
Large portion of total air sent to furnace to supply necessary
oxygen for the combustion.

25. Classification of fans
 Classification based on flow of medium:
 Axial flow fan
 Radial flow (or) Centrifugal flow
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Classification based on construction:
Induced draft fan (ID fan)
Forced draft fan (FD fan)
Primary air fan (PA fan)

26. DEAERATOR
 A Deaerator is a device that is widely used for the removal of
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oxygen and other dissolved gases from the feed water to steamgenerating boilers.
In particular, dissolved oxygen in boiler feed waters will cause
serious corrosion damage in steam systems by attaching to the
walls of metal piping and other metallic equipment and
forming oxides(rust). Dissolved carbon dioxide combines with
water to form carbonic acid that causes further corrosion.
There are two basic types of Deaerator
The tray-type (also called the cascade-type) includes a vertical
domed deaeration section mounted on top of a horizontal
cylindrical vessel which serves as the deaerated boiler feedwater
storage tank.
The spray-type consists only of a horizontal (or vertical)
cylindrical vessel which serves as both the deaeration section and
the boiler feedwater storage tank.

27. ESP (ELECTROSTATIC PRECIPITATORS)

28. ESP (ELECTROSTATIC PRECIPITATORS)
 An electrostatic precipitator (ESP), or electrostatic air cleaner is
a particulate collection device that removes particles from a flowing gas (such as air)
using the force of an induced electrostatic charge.
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Electrostatic precipitators are highly efficient filtration devices that minimally impede
the flow of gases through the device, and can easily remove fine particulate matter such
as dust and smoke from the air stream.
 Basic Principles
 Electrostatic precipitation removes particles from the exhaust gas stream of an industrial
process. Often the process involves combustion, but it can be any industrial process that
would otherwise emit particles to the atmosphere. Six activities typically take place:
 Ionization - Charging of particles
 Migration - Transporting the charged particles to the collecting surfaces
 Collection - Precipitation of the charged particles onto the collecting surfaces
 Charge Dissipation - Neutralizing the charged particles on the collecting surfaces
 Particle Dislodging - Removing the particles from the collecting surface to the hopper
 Particle Removal - Conveying the particles from the hopper to a disposal point

29. STEAM TURBINES

30. Stream turbine
 A steam turbine is a device that extracts thermal energy from pressurized steam and
uses it to do mechanical work on a rotating output shaft. Its modern manifestation was
invented by Sir Charles Parsons in 1884
 Because the turbine generates rotary motion, it is particularly suited to be used to drive
an electrical generator – The steam turbine is a form of heat engine that derives much of
its improvement in thermodynamic efficiency from the use of multiple stages in the
expansion of the steam, which results in a closer approach to the ideal reversible
expansion process.
 Principle of operation
 An ideal steam turbine is considered to be an isentropic process, or constant entropy
process, in which the entropy of the steam entering the turbine is equal to the entropy of
the steam leaving the turbine. No steam turbine is truly isentropic, however, with typical
isentropic efficiencies ranging from 20–90% based on the application of the turbine.
 The interior of a turbine comprises several sets of blades, or buckets as they are more
commonly referred to. One set of stationary blades is connected to the casing and one
set of rotating blades is connected to the shaft. The sets intermesh with certain
minimum clearances, with the size and configuration of sets varying to efficiently exploit
the expansion of steam at each stage.

31. Difference between
impulse and reaction turbine

32. Thermal plant efficiency
 Thermal plant efficiency (or) overall plant efficiency is
the ratio of the energy output to the energy input to
the thermal power plant (Energy output is measured at
the terminal and energy input is the calorific value of
the fuel). This efficiency of the thermal power plant
can be expressed as the product of the efficiencies of
its subsystem:
Thermal plant= boiler × cycle × internal turbine × mechanical turbine × generator

33. CONDENSER
Schematic layout of a typical surface condenser

34. CONDENSER
 Steam-electric power plants utilize a surface condenser cooled by
water circulating through tubes. The steam which was used to turn
the turbine is exhausted into the condenser. The steam is therefore
condensed as it comes in contact with the cool tubes full of
circulating water.
 This condensed steam is withdrawn from the bottom of the surface
condenser. The condensed steam is now water, commonly referred
to as condensate water
 For best efficiency, the temperature in the condenser must be kept
as low as practical in order to achieve the lowest possible pressure
in the condensing steam. Since the condenser temperature can
almost always be kept significantly below 100 oC where the vapor
pressure of water is much less than atmospheric pressure, the
condenser generally works under vacuum.
 Thus leaks of non-condensable air into the closed loop must be
prevented

35. PUMPS
 CONDENSATE EXTRACTION PUMPS
 VACUUM PUMPS
 BOILER FEED PUMPS
 CENTRIFUGAL PUMP

36.  CONDENSATE PUMP
 A condensate pump is a specific type of pump used to pump
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the condensate (water) produced in an HVAC (heating or
cooling), refrigeration, condensing boiler furnace or steam system.
They may be used to pump the condensate produced from
latent water vapor in any of the following gas mixtures:
Conditioned (cooled or heated) building air
Refrigerated air in cooling and freezing systems
Steam in heat exchangers and radiators
The exhaust stream of very-high-efficiency furnaces
 VACUUM PUMPS
 A vacuum pump is a device that removes gas molecules from a
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sealed volume in order to leave behind a partial vacuum. The first
vacuum pump was invented in 1650 by Otto von Guericke, and
was preceded by the suction pump, which dates to antiquity.
Pumps can be broadly categorized according to three techniques
Positive displacement pumps
Momentum transfer pumps
Entrapment pumps

37.  BOILER FEED PUMPS
A boiler feedwater pump is a specific type of pump used to
pump feedwater into a steam boiler. The water may be freshly supplied
or returning condensate produced as a result of the condensation of the
steam produced by the boiler. These pumps are normally high pressure
units that take suction from a condensate return system and can be of
the centrifugal pump type or positive displacement type.
 CENTRIFUGAL PUMPS
Centrifugal pumps are a sub-class of dynamic ax symmetric workabsorbing turbo machinery. Centrifugal pumps are used to transport
fluids by the conversion of rotational kinetic energy to the
hydrodynamic energy of the fluid flow. The rotational energy typically
comes from an engine or electric motor. The fluid enters the pump
impeller along or near to the rotating axis and is accelerated by the
impeller, flowing radially outward into a diffuser or volute chamber
(casing), from where it exits.
 Common uses include water, sewage, petroleum and petrochemical
pumping. The reverse function of the centrifugal pump is a water
turbine converting potential energy of water pressure into mechanical
rotational energy.

38. Typical specifications of boiler feed pump:
 1. Motor driven BFP:
 Number
 Make
 Voltage
 BHP
 Speed
 Full load current
 Starting current
 Full load efficiency
 Power factor
 Type of bearing
:
:
:
:
:
:
:
:
:
:
one for each pump
M/s Hitachi
3300 V AC
1340 kW
3000 rpm
275 Amps
1255 Amps
95%
85%
forced oil lubrication

39.  2. Turbine driven BFP:
 Make
:
 Type
:
M/s Hitachi Limited
horizontal, single
cylinder, single stage
back pressure
 Maximum speed
:
 Minimum speed of unit
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including the gear box
Steam supply
Pressure
Temperature
Exhaust pressure
Wheel diameter
No. of stages
Critical speed
6041/2880 rpm
:
3021/1440 rpm
:
:
:
:
:
:
87.9kg/cm*cm
510 C
3-4kg/cm*cm
650mm
1(one)
7600rpm

40. Other components
 Ejectors
Generators

41. Ash handling plant

42. Ash handling plant
 System Description
The ash handling system handles the ash by bottom ash handling system,
coarse ash handling system, fly ash handling system, ash disposal system up to
the ash disposal area and water recovery system from ash pond and Bottom ash
overflow. Description is as follows:
A. Bottom Ash Handling System
 Bottom ash resulting from the combustion of coal in the boiler shall fall into
the over ground, refractory lined, water impounded, maintained level, double
V-Section type/ W type steel- fabricated bottom ash hopper having a hold up
volume to store bottom ash and economizer ash of maximum allowable
condition with the rate specified. The slurry formed shall be transported to
slurry sump through pipes.
B. Coarse Ash (Economizer Ash) handling System
 Ash generated in Economizer hoppers shall be evacuated continuously through
flushing boxes. Continuous generated Economizer slurry shall be fed by gravity
into respective bottom ash hopper pipes with necessary slope.

43. C.
Air Pre Heater ash handling system
 Ash generated from APH hoppers shall be evacuated once in a shift by vacuum
conveying system connected with the ESP hopper vacuum conveying system.
 D.
Fly Ash Handling System
 Fly ash is considered to be collected in ESP Hoppers. Fly ash from ESP hoppers
extracted by Vacuum Pumps up to Intermediate Surge Hopper cum Bag Filter
for further Dry Conveying to fly ash silo.
 Under each surge hopper ash vessels shall be connected with Oil free screw
compressor for conveying the fly ash from Intermediate Surge Hopper to silo.
Total fly ash generated from each unit will be conveyed through streams
operating simultaneously and in parallel.
 E.
Ash Slurry Disposal System
 Bottom Ash slurry, Fly ash slurry and the Coarse Ash slurry shall be pumped
from the common ash slurry sump up to the dyke area which is located at a
distance from Slurry pump house.

44. Conclusion
 All the components and parameters of various
equipment involved in the power generation are
observed.
 In the case study parameters like condenser duty,
vacuum efficiency, cooling water flow, latent heat,
performance of condenser and effect of vacuum
analyzed and comparison are made.