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FAMILIARIZATION OF POWER PLANT
ALONG WITH ITS VARIOUS ASPECTS
Under the guidance of
Mrs. Santosh Sahran AEE/C&I-I
HPGCL (Haryana Power Generation
Corporation Limited) was incorporated as
company on March 17, 1997 and was given
the responsibility of operating and
maintenance of State's own generating
projects. One of them is Rajiv Gandhi
Thermal Power Plant (RGTPP), Khedar.
It was commissioned on August 24, 2010.
It has two units each with a generating power
of 600 MW. This means that total generation
of the plant per day is 1200 MW.
At present 60% of total electricity
production in India is from Coal Based
Thermal Power Station. A coal based
thermal power plant converts the
chemical energy of the coal into
electrical energy. This is achieved by
raising the steam in the
boilers, expanding it through the
turbine and coupling the turbines to
the generators which converts
mechanical energy into electrical
WHY COAL ?
• Low cost
• Technology for generation well
• Easy to mine, transport and store
• Economically possible to set up coal
• Produces high energy upon
But there are certain disadvantages
related to coal
• Non-renewable and fast depleting
• Lowest energy density per unit volume, meaning
that the amount of energy generated per cubic
meter is lower than any other fossil fuel
• High coal transportation costs due to the bulk of
• Produces large number of pollutants
• Coal dust is an extreme explosion hazard, so
transportation and storage must take special
precautions to mitigate this danger
Heat Loss In
COAL TO ELECTRICITY……..
•The coal is brought and crushed to powder. This is feed
to furnace for producing heat
•In Boiler drum 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
•The Exhausted steam is sent to reheater and the steam
then rotates the Intermediate pressure(IP) Turbine
•The steam from the IP turbine is then feed to low
•The turbine shaft is connected to the Generator, which
produces Electric Power.
•The power generated is then Transmitted.
RANKINE CYCLE – THE WORKING
PRINCIPLE OF THERMAL POWER PLANTS
ALL OVER THE WORLD
Starting at 1, the water at room temperature is
boiled at constant temperature in the boiler. This
process has a T constant for it is the boiling of
water which takes at a constant temperature.
Here we are increasing the entropy of by phase
change. The end product is steam. The steam must
be heated to higher temperatures. This phase is
called super heater and this phase is mainly
executed in ‘super heater’. The source of heat for
the super heater is the hot flue gases obtained in
the boiler after burning coal. This explains the
phase 2-3 in the T-S curve. in the next
process, the super heated steam is allowed to
expand in the turbine. As, the high pressure steam
is allowed through a small nozzle ,steam acquires
This kinetic energy of the steam will exert
required force on the turbine blades. This process
is a constant entropy process. Now the output of
the turbine is low pressure and low temperature
steam. This accounts for the phase 3-4 of the
cycle. Now steam is changed to hot water in
condenser without any temperature change. This
accounts for the phase 4-5 of the cycle. The step
5-6 is a pump which is used to circulate water.
During this process, a little temperature change
can be observed. Finally, the cooled water cannot
be directly sent into boiler. Hence, the water
should be heated to higher temperature. This is
done in economizer which uses heat from flue
gases. Thus this accounts for the 6-1 phase of
the Rankine cycle.
A Boiler or steam generator essentially is a
container into which water can be fed and
steam can be taken out at desired pressure
(172-180 kg), temperature (540°
C) and flow.
This calls for application of heat on the
container. For that the boiler should have a
facility to burn a fuel and release the heat. The
functions of a boiler thus can be stated as:-
• To convert chemical energy of the fuel into
• To transfer this heat energy to water for
evaporation as well to steam for superheating.
• Light diesel oil (LDO)
• Heavy fuel oil (HFO)
Light diesel oil is fuel of intermediate
viscosity. Preheating may be
necessary in some equipment for
burning and, in colder climates, for
handling. It is also costly.
Heavy fuel oil is a fuel more viscous
than Light diesel oil but intended for
similar purposes. Preheating is
usually necessary for burning and, in
colder climates, for handling. It is
less costly than LDO
KINDS OF OIL USED IN
Super heater :
The steam is super heated in order to make it hold
more energy and transfer it to the turbine. This
job is accomplished by the super heater. Super
heater is showed in the boiler schematic. The flue
gases coming out of the boiler are used to super
heat the steam.
The water entering into the boiler must have a
temperature compatible with the boiler
temperature. So, the heat left with the flue gases
after superheater is used to heat the water in the
economizer. The economizer has convoluted tubes
in which water flows and the flue gases flow over
these tubes in a closed structure.
Power plant furnaces may have a reheater section containing tubes heated
by hot flue gases outside the tubes. Exhaust steam from the high pressure
turbine is rerouted to go inside the reheater tubes to pickup more energy
to go drive intermediate or lower pressure turbines.
Ash handling system
The disposal of ash from a large capacity power station is of same
importance as ash is produced in large quantities. Ash handling is a major
i) Manual handling: The ash is collected directly through barrows from the
ash outlet door from the boiler into the container from manually.
ii) Mechanical handling: Mechanical equipment is used for ash
disposal, mainly bucket elevator, belt conveyer.
iii) Electrostatic precipitator: From air preheater this flue gases (mixed
with ash) goes to ESP. The precipitator has plate banks (A-F) which are
insulated from each other between which the flue gases are made to pass.
The dust particles are ionized and attracted by charged electrodes
Back to slide 43
In thermal Power Plant generally 3 turbines are used to increase the efficiency.
High Pressure Turbine(HPT): The superheated steam is directly fed to this
turbine to rotate it.
Intermediate Pressure Turbine(IPT): The out put from the HPT is reheated in a
reheater(RH) and used to rotate IPT .
Low Pressure Turbine(LPT): The Exhausted steam from the IPT is directly fed to
rotate the shaft of LPT.
*All the turbines are connected to a single shaft which is connected to the
The Synchronous Generator is used to Generate power by connecting
the shaft of the Turbine to the shaft of the generator which cuts the
magnetic flux producing mf.
The Generated Voltage will generally 11KV to 20 KV max. here 20KV
The Generated Voltage is stepped up by connecting Step up
transformer (here 400KV) and is transmitted and is also used for
Unit Auxiliary Transformer: This transformer is used to step down the
produced voltage and use for Auxiliary purpose.
BOILER FEED PUMP
Boiler feed pump is a multi stage pump provided for pumping
feed water to economiser. BFP is the biggest auxiliary
equipment after Boiler and Turbine. It consumes about 4 to 5
% of total electricity generation.
The heat carried out with the flue gases coming out of
economiser are further utilized for preheating the air before
supplying to the combustion chamber. It is a necessary
equipment for supply of hot air for drying the coal in
pulverized fuel systems to facilitate grinding and satisfactory
combustion of fuel in the furnace
The condenser condenses the steam from the exhaust of the turbine
into liquid to allow it to be pumped. If the condenser can be made
cooler, the pressure of the exhaust steam is reduced and efficiency of
the cycle increases. Below shown is surface condensor which is used in
The cooling tower is a semi-enclosed device for evaporative cooling of
water by contact with air. The hot water coming out from the
condenser is fed to the tower on the top and allowed to tickle in form
of thin sheets or drops. The air flows from bottom of the tower or
perpendicular to the direction of water flow and then exhausts to
the atmosphere after effective cooling.
It is used to remove air which is entrapped in the water
molecules. It is very important part because the entrapped air
affects boiler drum badly and leads to corrosion.
Principle behind deareation: gas solubility decreases as
temperature rises till saturation temperature is achieved.
Therefore when steam interacts with water it rises the
temperature of water till saturation temperature.
There are total three pumps attached to Deareator. They
are Motor Driven Boiler Feed Pump (MDBFP) on standby and
two TDBFP (Turbine Driven Boiler Feed Pump).
MDBFP is costly and uses electricity for its operation.
Therefore it is used in the starting only. TDBFP is very
economical and is turbine driven. Tappings are taken from HP
turbines and LP turbines. Steam from those tappings is used
to drive TDBFP.
Two types of feed heater are there:
High pressure heater
Low pressure heater
H P Heater is installed after Boiler feed pump
and it heats the feed water by exchanging heat
with the steam that is extracted from the H.P.
Turbine from different stages at different
L P heater is installed after condensate
extraction pump and in the same way it heats
the water but it takes the steam extraction
from the L.P. turbine.
Atmospheric air from PA fan
is mixed with coal and fed in
FD fan supports combustion
ID fan is the outlet or
exhaust. Already present air in
furnace is sucked by ID fan
and thrown out.
Three kinds of fans are there:
• Primary air fan
• Forced draft fan
• Induced draft fan
(Steam and Water Analysis System)
Different samples of water and steam are taken for
testing its various aspects.
•Dissolved oxygen transmitters
There are ten HIS (Human Interface Station) in
each unit. These HIS are:
•Engineering station (one)
•SOE – Sequence of Events (one)
•Performance calculation (one)
•Operation systems (five)
In addition to HIS, we have twenty three FCS
(Field Control Station) in each unit.
The termination pannel contains electronic cards
which are responsible for every type of
• AI card (analog input)
• AO card (analog output)
• DI card (digital input)
• DO card (digital output)
MEASUREMENTS TAKEN IN
• Analysis of water, steam and flue
•Steam at superheater inlet and outlet
•Feed water at economizer inlet
•Coal mill inlet and outlet
•P A fan, I D fan
•L P, H P heaters
•Reheated steam at outlet of reheater (LHS)
•Reheated steam at outlet of reheater (RHS)
•Saturated steam (RHS)
•Saturated steam (LHS)
•Super heated steam (RHS)
•Super heated steam (LHS)
•Feed water at economizer inlet
•Boiler water (left side)
•HP heater drain
•LP heater drain
•Electric generator cooling water