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SUBMI
TTED BY:
PALAK GOYAL
08BEC232
E
CE FINAL YEAR
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Acknowledgements
Everything that happens in the world is an
outcome of interaction of various factor, some of
which are favorable while others are not. Always
for a desired result, the number of favorable
factors is more. This work is NO exception to thisfact. I acknowledge that Ive been fortunate
enough to get the support, mentally and
physically in everything that I do.
First of all I would
like to thank Shri Anup Roy choudhary (chairman
NTPC, Korba) who led the entire team for
functioning of each department in a modernizedand techno-commercial atmosphere to make the
project touch such peaking performance. I would
give special thanks to Mr. Bimal Shah (HR) and
Mr.A.K.Singh (Sr Engg), for giving his very kind
permission to undergo the training programme
under the able guidance of NTPC engineers. All
these people were of immense importanceregarding the knowledge and supports for the
well furnished equipments.
I greatly
acknowledge the help and the mental strength
provided by my entire family, VIT University and
friends for encouraging me and providing meknowledge & guidance related with every
department of NTPC, KORBA.
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Contents
1. INTRODUCTION TO NTPC
2. ABOUT NTPC , KORBA
3. IMPORTANT ELEMENTS
COAL SOURCE
WATER SOURCE
LAND
FINANCIAL FACETS
HUMAN RESOURCE DEVELOPMENT
ENVIRONMENT PROTECTION
ASH UTILIZATION
4. COAL HANDLING PLANT
GRADING OF COAL
TURBINE
COOLING TOWER
COAL CYCLE
5. WORKING PRINCIPLE
6. PRODUCTION OF ELECTRICITY
7. GENERATOR AND TRANSFORMER
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8. OIL SYSTEM
9. GENERATOR PROTECTION
10. DISTRIBUTION OF ELECTRICITY
TRANSFORMER
SWITCHYARD
CIRCUIT BREAKER
11. DEMINERAL PLANT
12. ENVIRONMENT PROTECTION MEASURE
13. EFFICIENCY
14. CONCLUSION
1. INTRODUCTION TO NTPC
Established in 1975, NTPC the largest power company of
the country, has been consistently powering the growth of
India.With an installed capacity of 30,144 MW, it
contributes 28.6% of the nations power generation. An
ISO 9001:2000 certified company, it is worlds sixth
largest thermal power generator and second most efficient
in capacity utilization.Rated as one of the Best companies
to work for India it has developed into a multi-location
and multi-fuel Company over the past three decades. The
emergence of Korba NTPC as one of the largest power
station in the country with an installed capacity of 2100
MW had put NTPC a step ahead in its Endeavour to meet
the ever-growing demand of electricity in the country.
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2. ABOUT NTPC- KORBA
LOCATION:The Korba Project is located on western bank ofHasdeo River at a distance of approx. 10kms from Korba in the
Korba District of Chhattisgarh.
INSTALLED CAPACITY:
Stage 1: Three 200 MW
Stage 2: Three 500 MW
Stage 3: One 500 MW (All in operation.)
BENEFICIARY STATES:
MADHYA PRADESH, CHHATTISGARH, DAMAN AND DIU,
MAHARASHTRA, GUJRAT & GOA.
3.IMPORTANT ELEMENTS:
A.COAL SOURCE
The coal is supplied by Gevra Mines of South Eastern Coal
Fields through a
34 km long Merry-Go-Round (M.G.R). Railway System. Annualcoal requirement for Stage-1 & 2 is 12 MMT. The average
calorific value of the coal is approx. 3500 kcal/kg .
MERRY-GO-ROUND (M.G.R) SYSTEM
SILOS
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TRACK HOPPER
TOTAL TRACK LENGTH: 34.80 KM
LENGTH OF LOAD LINE: 14.86 KM
LENGTH OF EMPTY LINE: 19.94 KM
TRACKHOPPER:-
When a rake reaches trackhopper,unloading of coal is done
manually by given a DC supply to each wagon.When a dc
supply is given to a wagon ,its bottom gate opens and coal is
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emptied into a trackhopper.Time taken for unloading each
wagon is 20seconds. There are total 2 trackhoppers though
only one works all the time . The 2nd trackhopper is used in case
of failure operation of 1st trackhopper. It has a capacity of 3000
tons.
PADDLE FEEDER:-
It is used to move coal from track hopper to bunker. These are
situated below trackhopper and when wagon is emptied it cuts
the coal into size
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6 mines per unit.There are 3 units of stage 2 with Capacity 500
MW and coal is taken from 9 mines per unit.
STACK YARD:-
Stack yard is the place where coal is stacked & reclaimed if
needed. Its done by using Staker & Reclaimer. A stack yard
consists of Bucket wheel and Boom conveyor. Capacity of stack
yard is 7 ton. Hence, it can be used for 19-20 days.
B.WATER SOURCE
The huge requirement of this project is being met by right sideof Hasdeo River and Bango dam on the up-stream of the
Hasdeo River. The daily water requirement for the station is as
follows:
Service Water & Fire water 46,600
Cu.m/day
Cooling Water 96,000
Cu.m/day
Processing 2,400
Cu.m/day
Domestic 10,000
Cu.m/day
Others(ash water)- Stage 1 25,000
Cu.m/day
Total
80,000 Cu.m/day
C.LAND
The total 4,826 acres of land is required for the
construction of plant including the land required for stage
2 Ash Dyke. The detail of land acquired is as follows:
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Area wise detail of land Land
(in Acres)
1. Main Plant and Existing Ash Dyke
2601
2. Permanent Township
447
3. M.G.R
517
4. Link Road
35
5. Stage 2 Ash Dyke
1226
Total
4826
D. FINANCIAL FACETS:
1. PROJECT COST
It involves total investment of Rs 1625.25 crores for
its capacity of 2100 MW.
2. FINANCIAL ASSISTANCE
The Foreign Assistance available for this
project includes:
Description Unit AMOUNT
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IDA Credit US $/Million 200.00
OPEC Credit US $/Million 20.00
IDACredit(W.Germany)
US $/Million 316.40
KFC Credit US $/Million 173.40
E. HUMAN RESOURCE DEVELOPMENT
The Human Resources Development has always been
accorded supreme priority. In the context of NTPCsobjective of operating a highly capitalized industry, special
emphasis has been laid towards training and development
of its engineers, supervisors and technicians to keep up
with the latest technological development in the power
sector . It has always laid special emphasis on the training
& development of its employees.
F.ENVIRONMENTAL PROTECTION
Realising the need to live with nature in harmony,
maintenance of ecological balance has always been a
priority. All the units have been provided with high
efficiency Electrostatic Precipitation. More than 1.5 Million
trees have been planted in & around the plant. Liquid
Waste Treatment plant for treating ash water, Coal
handling plant Effluents etc have been established.
G. ASH UTILISATION
NTPC has been giving top most priority for maximising Ash
Utilisation. Ash is used for raising the Ash Dyke, issued to
Cement Industries and for making bricks. Six bricks
making plants each with a capacity of 10,000 bricks
/machines/day has been installed inside the plant & is
given to cooperative society for making bricks. More than
1 million bricks are produced annually.
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COAL HANDLING PLANT (C.H.P)Raw materials required for coal handling plant are Coal,
Oil, Air and Water. Coal is the major source of energy.
The flowchart representing the generation of electricity
is shown below:-
The Capacity of NTPC Thermal Power Plant is 21
MW.
Grading of Coal:-
Serial no. Grade Calories per kg
1 A >6200 Kcal/kg
S W I T C H Y
G E N E R A T O R
G E N E R A T
T U R B I N E
B O I L E R
P U L V E R I Z
B U N K E R
C R U S H E R
T R A C K H O P
M G R
M I N E S
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2 B 5600-6200 kcal/kg
3 C 4490-5600 kcal/kg
4 D 4200-4490 kcal/kg
5 E 3360-4200 kcal/kg
6 F 2400-3360 kcal/kg
7 G 1300-2400 kcal/kg
TURBINE:-
It is a form of engine, which requires a suitable working fluid in
order to function. When fluid flows through it, a part of energy
is converted into required mechanical energy.Steam & gas
turbine uses heat energy whereas water turbine uses pressure
energy. The turbines are used at High Pressure, Medium
Pressure and Low Pressure.
COOLING TOWER:
For 200 MW unit two CT pumps are provided having
15000 m3/hr discharge capacity and speed of 500 rpm.
Each Cooling tower has height 30m with 16 induced draft
fans having 27000 m3/hr flow rate and cooling range up to
10 oC.
COAL CYCLE
C.H.P Plant Bunker Feeder Pulverization millBoiler section
Feeder: It is an induction motor driven device, which
determines the Quantity of coal that should enter in the
pulverize mill.
Pulverization mill: Pulverization means exposing a
large surface area to the action of oxygen.
Working Principle: -
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The working principle of a steam plant is based on
Rankine cycle. Steam is the working medium as it is stable.
A graph plotted between the temperature and the entropy
would indicate the technical details of the working by the
rankine cycle.
PLANT FLOW DIAGRAM
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Meanwhile the heat released from the coal has been
absorbed by the tube on the boiler walls. Inside the tube,
boiler feed water is transformed by heat into the steam
at high pressure and temperature.
The steam super-heated tube passes to the turbine
where it is discharged through the nozzles on the turbine
blades. The energy of the steam, striking the blades,
makes the turbine rotate.
Coupled to the end of the turbine is the rotor of the
generator a large cylindrical magnet, so that when the
turbine rotates the rotor turns with it.
The rotor is housed inside the stator having heavy coils of
copper bars in which electricity is produced through the
movement of the magnetic field created by the rotor. The
electricity passes from the stator winding to the step-up
transformer which increases its voltage so that it can be
transmitted efficiently over the power lines of the grid.
The steam which has given up its heat energy is changed
back into water in the condenser so that it is ready for
reuse. The condenser contains many long cooling tubes.
The steam passing around the tubes looses the heat and
is rapidly changed back to water.
But the two sections of water (i.e. boiler feed water &
cooling water) must NEVER MIX. The cooling water is
drawn from the river but the boiler feed water must be
absolutely pure, far purer than the water we drink.
To condense the large quantities of steam, huge and
continuous volume of cooling water is essential. In most of
the power stations the same water is used over and over
again. So, the heat which the water extracts from the
steam in the condenser is removed by pumping the water
out to the cooling towers.
The cooling towers are simply concrete shells acting ashuge chimneys creating a draught of air. The water is
sprayed out at the top of towers and as it falls into the
pond beneath it is cooled by the upward draught of air.
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The cold water in the pond is then circulated by pumps to
the condensers. However, some of the water is drawn
upwards as vapours by the draught and forms the familiar
white clouds which emerge from the towers seen
sometimes.
Why should one bother to change steam from the turbine back
into water if it has to be heated up again immediately? The answer lies in the law of physics which states that the
boiling point of water is related to pressure. The lower the
pressure, the lower the temperature at which water boils. The
turbine designer want as low boiling point of water as possible
because he can only utilize the energy of the steam when the
steam changes back into water he can get NO more work out of
it. So a condenser is built, which by rapidly changing the steam
back into water creates a vacuum. This vacuum results in a
lower boiling point which will give steam well below 100oC.
GENERATORS AND TRANSFORMER:
TURBO GENERATOR
KVA 247000
Power factor 0.85
Stator voltage 15750
Stator current 9050
Rotor voltage 310
Rotor current 2600
RPM 3000
Hz 50
Phase 3
Connection YY
Coolant Water (stator)& hydrogen
(rotor)
Gas pressure 3.5kg/cm-sq.
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TWO TYPES OF OIL SYSTEM:
1.SEAL OIL SYSTEM Hydrogen in the generator is under very
high pressure. Seal oil is used to seal the gaps so that hydrogendoesnt come out.
2. LUBRICATION OIL SYSTEM- Pumps are used to circulate
lubrication-oil inside the generator. Turbine lubrication oil
system seeks to provide proper lubrication of turbo generator
bearings.
GENERATOR PROTECTION
1.STATOR PROTECTION-The neutral of star connected
winding is connected to primary of neutral grounding
transformer, so that earth fault current is limited by over
voltage relay.
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STATOR PROTECTION
2.DIFFERENTIAL PROTECTION- In case of phase-to-phase
fault, generator is protected by longitudinal differential relay.
DIFFERENTIAL PROTECTION
WORKING:
Under normal conditions or for a fault outside of the protectedzone, current I1 is equal to current I2 . Therefore the currents in
the current transformers secondaries are also equal, i.e. i1 =
i2 and no current flows through the current relay.
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3. ROTOR PROTECTION-The Rotor winding is damaged by
earth faults or open circuits. The field is biased by a dc voltage,
which causes current to flow through the relay for an earth
fault anywhere on the field system. It short circuits the rotor
winding and therefore, produce an unsymmetrical field systemand unbalance force on the rotor. This causes vibration of the
rotor and damage to the bearings. So rotor earth fault
protection is provided to restrict the fault spreading.
4. OVER SPEED PROTECTION- Mechanically over speed
device that is usually in the form of centrifugally operated rings
mounted on the rotor shaft, which fly out and closes the stop
valves if the speed of the system increases by more than 10%.
5. OVER VOLTAGE PROTECTION - It is provided with an over
voltage relay. The relay is usually induction pattern. The relay
open the main circuit break and the field switch if the over
voltage persists. It uses just four components: a silicon
controlled rectifier or SCR, a zener diode, a resistor and a
capacitor.
Working :When the zener diode voltage is reached, current
will flow through the zener and trigger the silicon controlled
rectifier or thyristor. This will then provide a short circuit to
ground, thereby protecting the circuitry.
DISTRIBUTION OF ELECTRICITY:-
TRANSFORMER
TYPES:
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1. GENRATOR TRANSFORMER :- It is a step up
transformer that gets its primary supply from generator
and its secondary supplies the switchyard from where it
is transmitted to grid. This transformer is oil cooled. The
primary is connected in star and the secondary in deltaform.
2. STATION TRANSFORMER:-This transformer has almost
the same rating as the generator transformer. Its primary
is connected in delta and secondary in star. It is a step
down transformer.
3. UNIT AUXILIARY TRANSFORMER:- It is a step down
transformer. The primary receives from generator andsecondary supplies a 6.6 KV bus. This is oil cooled. These
are 8 in number.
4. NEUTRAL GROUNDED TRANSFORMER:- This
transformer is connected with supply coming out of UAT
in stage 2. This is used to ground the excess voltage if
occurs in the secondary of UAT in spite of rated voltage.
SWITCH YARD
As we know that electrical energy cant be stored like cells, sowhat we generate should be consumed instantaneously. But as
the load is not constant therefore, we generate electricity
according to need i.e. the generation depends upon load. The
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yard is the place from where the electricity is sent outside. It
has both outdoor and indoor equipments.
SINGLE LINE DIAGRAM OF 220KV SWITCH YARD:
OUTDOOR EQUIPMENTS
It includes BUS BAR, LIGHTENING ARRESTER, WAVE TRAP,
BREAKER, CAPACITOR VOLTAGE TRANSFORMER, CORONA
RING, EARTHING ROD, CURRENT TRANSFORMER, POTENTIAL
TRANSFORMER and LIGHTENING MASK.
INDOOR EQUIPMENTS
It includes RELAYS and CONTROL PANELS.
CIRCUIT BREAKER:
Circuit breaker is an arrangement by which we can break the
circuit or flow of current. A circuit breaker in station serves the
same purpose as switch but it has many added and complex
features. The basic construction of any circuit breaker requires
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the separation of contact in an insulating fluid that serves two
functions:
1. It extinguishes the arc drawn between the contacts when
circuit breaker opens.
2. It provides adequate insulation between the contacts and
from each contact to earth.
The insulating fluids commonly used in circuit breakers are
Compressed air, Oil which produces hydrogen for arc
excitation, Ultra high vacuum, Sulphur & hexafluorides.
LIGHTING ARRESTER:
It saves the transformer and reactor from over voltage and
over currents. Used in both primary and secondary of
transformer and in reactors.
A meter is provided that indicates:
1. Green arrester is healthy
2. Red arrester is defective
In case of red, we first de-energize the arrester and then do
the operation.
AIR BREAK EARTHING SWITCH:
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The work of this equipment comes into picture when we want
to shut down the supply for maintenance purpose. This helps to
neutralize the system from induced voltage from extra high
voltage. The induced power is up to 2KV.
BUS BAR:
Bus bars generally are of high conductive aluminium or copper
of adequate cross section located in air insulated enclosures &
segregated from all other components.
DEMINERAL PLANT
INTRODUCTION: --Water is required in plant for many
purposes like formation of steam, removal of ash, safety during
fire etc. But the water required for the formation of steam
should be perfectly devoid of minerals because if minerals are
present in the steam and the steam strike the blades of
the turbine, then due to high pressure, it produces scars or
holes on the turbine blades.
PURIFICATION OF WATER: -
Water is purified in DM plant through a chain of processes as
under: --
Carbon filter Water taken from the river is first sent to
the carbon filter for the removal of carbon contents in the
water.
Strong acid cation exchanger After passing through
the carbon filter, water is sent to the strong acid cation
exchanger, which is filled with the concentrated HCL. The
acid produces anions, which gets combined with the
cations present in the water.
Strong base anion exchanger After this the water is
sent to the strong base anion exchanger, which is filled
with the concentrated NaOH. The base produces cations,
which get combined with the anions present in the water.
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Mixed bed exchanger Now the water is sent to the
chamber of mixed bed exchanger where the remaining
ions are removed. This is the last stage of purification.
ENVIRONMENT PROTECTION MEASURES TAKEN BY
NTPC:
1. Electrostatic Precipitators: The ash left behind aftercombustion of coal isArrested in high efficiency Electrostatic Precipitators (ESPs) and
particulate emission is controlled well within the stipulated
norms. The ash collected in the ESPs is disposed to Ash Ponds
in slurry form.
2.Flue Gas Stacks:Tall Flue Gas Stacks have been provided
for wide dispersion of the gaseous emissions (SOX, NOX etc)
into the atmosphere.
3.Low-NOX Burners: In gas based NTPC power stations, NOx
emissions are controlled by provision of Low-NOx Burners (dry
or wet type) and in coal fired stations, by adopting best
combustion practices.
4.Neutralisation Pits: Neutralisation pits have been providedin the Water
Treatment Plant (WTP) for pH correction of the effluents before
discharge into Effluent Treatment Plant (ETP) for further
treatment and use.
5.Coal Settling Pits / Oil Settling Pits: Coal dust and oil are
removed from the effluents emanating from the Coal Handling
Plant (CHP), coal yard and Fuel Oil Handling areas before
discharge into ETP.
6.DE & DS Systems: Dust Extraction (DE) and DustSuppression (DS) systems have been installed in all coal firedpower stations in NTPC to extract the fugitive dust released inthe Coal Handling Plant (CHP).
7.Cooling Towers: Cooling Towers have been provided forcooling the hot Condenser cooling water in closed cycle
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Condenser Cooling Water (CCW) Systems. This helps inreduction of thermal pollution and conservation of fresh water.
8.Ash Dykes & Ash Disposal Systems: Ash ponds havebeen provided at all coal based stations where Dry Ash
Disposal System has been provided.Ash in slurry form is discharged into the lagoons where ash
particles get settled from the slurry and clear effluent water is
discharged from the ash pond.
9.Ash Water Recycling System:In the AWRS, the effluentfrom ash pond is circulated back to the station for further ashsluicing to the ash pond. This helps in savings of fresh waterrequirements for transportation of ash from the plant.
Monitoring and alarm system
Most of the power plant operational controls are automatic.
However, at times, manual intervention may be required. Thus,
the plant is provided with monitors and alarm systems that
alert the plant operators when certain operating parameters
are seriously deviating from their normal range.
Battery supplied emergency lighting and
communication
A central battery system consisting oflead acid cell units is
provided to supply emergency electric power to power plant's
control systems, communication systems, turbine tube oil
pumps, and emergency lighting. This is essential for a safe,
damage-free shutdown of all the units in an emergencysituation.
Efficiency
The energy efficiency of a conventional thermal power station
as a percent of the heating value of the fuel consumed is
typically 33% to 48%. This efficiency is limited as all heat
engines are governed by the laws ofthermodynamics. The rest
of the energy must leave the plant in the form of heat.
This waste heat can go through a condenserand be disposed of
with cooling water or in cooling towers.
http://en.wikipedia.org/wiki/Lead_acid_batteryhttp://en.wikipedia.org/wiki/Heating_valuehttp://en.wikipedia.org/wiki/Thermodynamichttp://en.wikipedia.org/wiki/Waste_heathttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Cooling_waterhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Lead_acid_batteryhttp://en.wikipedia.org/wiki/Heating_valuehttp://en.wikipedia.org/wiki/Thermodynamichttp://en.wikipedia.org/wiki/Waste_heathttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Cooling_waterhttp://en.wikipedia.org/wiki/Cooling_tower8/3/2019 Ntpc Final Report
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Conclusion
On completion of my implant training
at NATIONAL THERMAL POWER COMPANY, KORBA I have come
to know about how the basic necessity of our lives i.e.
electricity is generated. What all processes are needed to
generate and run the plant on a 24x7 basis.
NTPC KORBA is one of the plants in
India to be under highest load factor for the maximum duration
of time and is operating at highest plant efficiencies. This plant
is an example in terms of working efficiency and management
of resources to all other thermal plants in our country. This
training gave me an opportunity to clear my concepts from
practical point of view with the availability of machinery of such
large rating.Driven by its vision to lead, NTPC has charted out
an ambitious growth plan of becoming a 40,000 MW plus
company by 2012.
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