ntpc final report

8/3/2019 Ntpc Final Report

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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_tower


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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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ntpc final report

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