REPORT Electrical

7/27/2019 REPORT Electrical

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REPORT ON

SUMMER TRAINING

AT

NTPC FARIDABAD


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ACKNOWLEDGEMENT

I am thankful to NTPC for providing me an opportunity to get

an insight and practical experience in the operation, electrical

grid system, control and maintenance of power plant.

ACKNOWLEDGEMENT

I am extremely grateful to Mr. R.K. Niranjan (HRD-EDC)

under whose guidance this summer training was conducted

successfully. I feel highly indebted to all the senior NTPC

officials who extended me a constructive help in the technical

field.

I am thankful to

Mr K.K Sharma (Sr. Manager-Chemistry)Mrs. Prachi (Electrical maintenance)Mr N.N Mishra (AGM- O&M)Mr Manoj Agarwal (DGM- Mechanical maintenance)Mr Jimmy Joseph (S.S- C&I)Mr D.C Tiwari (S.S- Operation)

I gratefully acknowledge all the engineers/staff who gave us

their valuable time, encouragement, constructive criticism for

familiarizing us with all technical aspects of the power plant.


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Submitted To

Sandeep Tewatia

Mr. R.K Niranjan B-tech

3rd year

(HRD-EDE) Electricalengineering

Hinducollege of engineering

Sonepat-131001

Contents


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1. Overview of the Faridabad gas power station

2. Combined cycle power generation

3. Overview of the power plant

a) gas turbine system

b) Heat recovery steam generator

c) Steam turbine system

d) Condensate

e) Feed water system

4. Electrical systems

5. Mechanical systems

a) Gas turbine and auxillaries

b) Heat recovery steam generator

c) Steam turbine system and auxillaries

d) Condenser and auxillaries

e) Steam cycle charactersticks

f) Feed water system auxillaries

6. Control and Instrumentation

Overview of the Faridabad Gas PowerStation


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(i) Location : Faridabad GPP is located near village

Mujhedi & Neemka in Faridabad

district of Haryana State. The

Latitude & longitude of the site are

280 20 48 (N) & 770 2148 (E)

respectively.

(ii) Land Requirement : 321.45 acres of land has been

acquired (241.53 of Plant & 79.92 for

Township)

(iii) Plant Capacity : 431.586 MW

(GT: 2X137.758 MW + ST 1X156.07

MW)

(iv) Mode of operation : Base Load

(v) Fuel : Natural Gas (Main Fuel)

Naphtha (Alternate Fuel)

(vi) Gas requirement : Average 1.58 mcmd at 68.5% PLF2.30 mcmd at 100% PLF.

(vii) Gas transportation : To be piped from HBJ pipeline by

GAIL.

(viii) CW System : Closed cycle cooling water system

with Induced draft cooling towers

and make up water supply from high

level canal fed by tubewell operatedby Haryana State Minor Irrigation

Tubewell Corporation & Rampur

Distributory of Gurgaon canal.

(ix) Power Evacuation : Transmission System being built by

Power Grid.

(x) Beneficiary State : Haryana State

(xi) Project Cost (PowerPlant & Facilities)

: Rs. 1163.60 crore


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(xii) Cost of Generation : 205.82 paise / kwh

(xiii) Environmental

Aspects

:

Water Pollution : Liquid Effluents from plant and

township will be neutralized before

disposal.

Air Pollution : Emission of NOx will be limited

within 50 ppm during operation of

the plant with natural gas as

stipulated in the Environmental

clearance by MOEF.

(xiv) Project Financing : The project is being partly financed

by Govt. of India in the form of loanand equity. The fund from GOI is

being provided by JBIC, Japan to an

extent of 22171 million Yen. Balance

fund requirement will be met from

internal resources & Domestic

Commercial Borrowings (DCB).

(xvi) CommissioningSchedule

: Govt. App. Sch. Actual

GT#1 Jan 2000 June

1999

GT#2 Mar 2000 Oct. 1999

ST Jan 2001 July 2000

Combined cycle power generation


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COMBINED CYCLE

In combined/closed cycle, two combustion turbine-generators operate in conjunction

with two heat-recovery steam generators and a steam turbine-generator. In the first

cycle, fuel is burned and the resulting combustion gases power two turbine-

generators to produce electricity. Hot exhaust normally lost during this process is

captured and routed through the two heat-recovery steam generators. These unitsboil water to create steam, which spins an additional turbine-generator and

produces more electricity. Finally, the steam is discharged into a condenser, which

returns the steam to its liquid state for recycling.

At FGPS, the gas turbines installed are based on the Brayton Cycle while the steam

turbine is based on Rankine Cycle. These cycles are explained below.

BRAYTON CYCLE

Gas turbines operate on this cycle. In this cycle air is compressed in a compressor.

This compressed air is used for combustion and the combustion product is allowed to

expand in the turbine, which is coupled with the generator. In modern gas turbines

the temperature of the exhaust gases is in the range 500C to 580C.

RANKINE CYCLE

The conversion of heat energy to mechanical energy with the aid of

steam is carried out through this cycle, which involves:


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The initial state of the working fluid is water, which at certain

temperature is compressed by the pump and fed to the boiler.

In the boiler the compressed water is heated at constant

pressure.

Superheated steam is expanded in the turbine, which is coupled

with the generator.

COMBINING TWO CYCLES TO IMPROVE EFFICIENCY

We have seen in the above two cycles that the gas turbine exhaust is of 500C-580C

and in the Rankine cycle temperature required to generate is 500C-560C. So we

use the gas turbine exhaust to generate steam in the Rankine cycle and save fuel

required to heat the water.

ADVANTAGE OF THE COMBINED CYCLE PLANTS

Apart from the higher efficiency, the combined cycle power plants

have following advantages:

Low installation cost

Low gestation period

Better reliability

Low environmental pollution

If efficiency of gas turbine cycle (where natural gas is used as fuel)

is 31% (which is usually the case) and the efficiency of Rankine

cycle is 35%, then over all efficiency comes to 49%.

Overview of the power plant

Plant overview presents a broad picture on how the fuel is utilized to

generate power without going much in detail. It shows how the

different units of a power plant work in tandem to form a complex but

highly organized system, which is efficient and very reliable.


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Gas turbine system

The gas turbine is a common form of heat engine working with a

series of processes consisting of compression of air taken from

atmosphere, increase of working medium temperature by constant

pressure ignition of fuel in combustion chamber, expansion of SI and

Internal Combustion (IC) engines in working medium and combustion,but it is like steam turbine in its aspect of the steady flow of the

working medium.

For the gas turbine to produce any work, the hot gases must expand

from a high pressure to a low pressure. Therefore the gases must first

be compressed. If after the compression the fluid were expanded

through the turbine, the power produced would equal that used by the


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compressor, provided that both the turbine and compressor

functioned ideally.

If heat were added to the fluid before it reached turbine, raising its

temperature, then an increase in power output could be achieved. If

more and more thermal energy could be added to the fluid then more

and more power output could be produced. Unfortunately this cannot

occur as the turbine blades have metallurgical thermal limit. If the

gases continuously enter at a temperature higher than this, the

combined thermal and material stresses in the blades will cause them

to fail. Typically, inlet temperature of 1300K may be found in

industrial turbines and inlet temperatures in experimental models are

up to 1500K.

At P.P.C.L two gas turbines, Model 9E of make General Electric (GT1)

and Bharat Heavy Electrical Ltd. (GT2) are being used. The 9E is a

simple flow cycle, single shaft gas turbine with fourteen reverse-flow

combustion systems. The 9E assembly consists of six major section or

groups:

1. Air inlet.2. Compressor.

3. Combustion system.

4. Turbine.

5. Exhaust.

6. Support systems.

1. GAS PATH DESCRIPTIONWhen the turbine starting system is actuated and the clutch

is engaged, ambient air is drawn through air inlet plenum

assembly, which is then filtered & compressed in the 17-

stage, axial flow compressor. Then this compressed air from

compressor flow into the annular space surrounding the 14-

combustion chambers. From there, it flows into the

combustion liners for proper fuel combustion.


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Fuel for combustion is being supplied by Gail (Gas Authority of India

Ltd.) through HBJ (Hazirapur-Bijapur-Jagdishpur) gas line at a

pressure of 24Kg at 26oC.

This fuel is filtered for the removal of solid particles at the Gas

Conditioning Skid before being fed into 14 equal flow lines each

terminating at a fuel nozzle centered in the end plate of a separate

combustion chamber. Prior to being distributed to the nozzles the

fuel is accurately controlled to provide an equal flow into the 14

nozzle feed lines at a rate consistent with the speed and the load

requirements of the gas turbine. The nozzle introduces the fuel into

the combustion chamber where it is mixed with the combustion air.

This fuel air mixture is then ignited in one of the 14-chambers and

the flame thus produced is propagated to ignite other fuel

chambers through connecting cross-fire tubes. After the turbine

rotor approximates operating speed, combustion chamber pressure

causes the spark plugs to retract so as to remove their electrodes

from the hot flame zone.

The hot gasses from the combustion chambers expand into 14

separate transition pieces attached to the aft end of the

combustion chamber liners & flow from there to three-stageTurbine Section. Each stage consists of a row of fixed nozzles

followed by a row of routable turbine buckets. In each nozzle row,

the kinetic energy of the jet increases while the pressure drops &

each following row of moving buckets, a portion of kinetic energy of

jet turns the turbine rotor. Since the turbine is coupled to the

generator rotor, the resulting rotation of turbine is transferred to

generator, which generates the electrical power.

After passing the third stage buckets, the exhaust gasses (at about

570oC) are directed to the HRSG before being directed into exhaust

hood (at about 140oC). The exhaust hood contains a series of

turning vanes to turn the gasses from an axial direction to radial

direction to minimize the exhaust hood losses. The gasses are then

passed into the exhaust plenum & are expelled into atmosphere

through the exhaust stack.


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Heat recovery steam generator

The Heat Recovery Steam Generator (HRSG) is installed so as to

increase the overall efficiency of the plant. It works by using the

utilizing flue gases of the gas turbine instead of burning fuel to

produce steam which runs a steam turbine which has a generator

coupled with it to produce electric power. With HRSG, the efficiency of

the plant may be in excess of 48%.

The HRSG, installed at FGPS, is a horizontal, natural circulation, single

drum, dual pressure, unfired, water-tube boiler. It is designed to

generate steam quantities 190 T/hr for the HP drum and 40 T/hr for

the LP drum. The feed water temperature is approximately 275

degree Celsius for the HP drum while for the LP drum, it is, 150.1 C at

the designed point.

The gas turbine flue gases act as the heat source of the boiler. The

combustion products heat water in a boiler where it is converted to

steam. This steam drives the steam turbine, which is mechanically

coupled, to a generator.

The modern large sized boilers are of water-tube type design. In theseboilers, water flows inside the tubes and the hot flue gases flow

outside of them. The circulation of water through the tubes of the

boiler is forced circulation through the action of pumps.

Flue gas flow

Flue gases from the exhaust of the Gas turbine are at the temperature

of 540 degree Celsius and are generally at very high velocity.

Therefore the fluegases are passed through a diffuser where pressureincreases at the expanse of the velocity. Next the flue gases are

allowed to pass through diverter damper gates, which permit the flow

of gases out of the bypass chimney or towards the HRSG depending

upon the position of the gate. The flue gases then rise along the

height of the HRSG and are evenly distributed using mechanical

barriers like gas distribution screens for the horizontal flow of the flue

gases along the HRSG. The flue gases generally carry smoke, which

deposit on the water tube as soot and reduce the heat transfer and


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hence HRSG is provided with soot blowers namely FRSB full

retractable soot blowers and HRSBs as per requirements.

Salient Features and Operation

The boiler is divided into nine zones. In order of higher temperature,they are as follows:

1. HP Super heater-II

2. HP Super heater

3. HP Evaporator

4. HP Economizer II

5. LP Super heater

6. LP Evaporator7. HP Economizer I

8. LP economiser

9. Condensate preheater (CPH)

Feedwater at BFP discharge is then pumped separately via HP BFP and

LP BFP to the High Pressure (HP) and Low Pressure (LP) drums from

which HP and LP steam is derived respectively. The cycle for both the

HP and LP steam is basically the same. The water is first taken to therespective economizers to heat the water and then taken to the


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evaporator where the water is converted to steam. This steam is

further heated to produce superheated steam. This process takes

place in the respective super heaters. Now, there is a possibility that

the temperature of the HP steam becomes very high (more than the

specifications) as there are two super heaters. To prevent the steam

from attaining very high temperatures, a device called De-Super

heater is installed between the two super heaters. It works by

sprinkling water on the steam as the steam passes through it. This

lowers down the temperature but also wets the steam. The steam is

dried in the next superheated and hence the temperature of the

steam is controlled. De-superheated is used only when required and

the amount of water sprinkled is also controlled so as not to decrease

the temperature of the steam too low that the second superheated

cannot increase it to the optimum limit. This superheated steam is

then taken to the turbine where it is allowed to expand and cool and

do mechanical work on the turbine rotor. The expanded steam from

the HP steam still has sufficient amount of heat and is taken to the LP

turbine. The steam from the LP turbine is taken to the Condenser

where it is converted back to water, as we cannot pump steam. The

water is extracted from the condenser by the Condensate Extraction

Pump (CEP). The water is extracted from the condenser as there is low

pressure (vacuum, maintained by vacuum pumps) inside the

condenser which has to be maintained otherwise there is a risk of

back-flow of steam back to the turbine. So the difference in pressure

has to be maintained and water has to be forced out. A part of the

steam is also tapped to seal the turbine, which is cooled in the Gland

Steam Cooler (GSC). The sealing is very critical as the difference in

pressure is quite large between that inside the turbine and the

outside. The steam has the tendency to escape and to prevent that

we require the sealing. The water from the condenser and GSC is

pumped together back to the condensate pre-heater and the cycle

begins again.

Everything in the plant works on a closed cycle to increase efficiency

and maintain economical production. The de-mineralized water is

produced after a long process involving dozing, filtering, reverse

osmosis, ion exchangers, etc. which makes the water purification

expensive. So, this water is not wasted and re-used. Only a small

amount of make-up water is taken from the plant. The condensing


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water (from LSP) in the condenser is cooled again and re-used to

condense steam to water in the condenser.

Steam turbine system

The turbine is a tandem compound machine with High Pressure (HP)and Low Pressure (LP) sections. The HP section is a stage flow turbine

whereas the LP section is a double flow. Rigid couplings connect the

individual turbine rotors and generator rotor.

The HP turbine has been constructed for throttle control governing.

The initial steam is admitted before the blading by two combined main

steam stop and control valves.

The steam from HP turbine exhaust is led to the LP turbine throughcross-around pipes. Additional steam from LP stage of waste heat


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recovery steam generator is passed to the LP turbine via two-

combined LP stops and control valves.

HIGH PRESSURE (HP) TURBINE

The HP turbine is of single flow, double shell, construction with

horizontally split casing. Allowance is made for thermal movement of

the inner casing within the outer casing. The main steam enters the

inner casing from top and bottom. The provision of an inner casing

confines high steam inlet temperature and pressure conditions to the

admission section of this casing, while the joint flange of the outer

casing is subjected only to the lower pressure and temperature

effective at the exhaust from the inner casing.

LOW PRESSURE (LP) TURBINE

The casing of the double flow LP turbine is of three-shell design. The

shells are of horizontally split-welded construction. The inner casing,

which carries the first rows of stationary blades, is supported on the

inner-outer casing so as to allow for thermal expansion. The inner-

outer casing rests at four points on longitudinal girders, independent

of the outer casing. Three guide blade carriers, carrying the last guideblade rows are bolted to the inner-outer casing.

BLADING

The entire turbine is provided with reaction blading. The moving

blades of the HP turbine and the initial rows of the LP turbine with

inverted T-roots and integral shrouding are machined from solid

rectangular bars. The last stages of the LP turbine consist of twisted,drop forged moving blades with fir-tree roots inserted in

corresponding grooves of rotor.

Like the moving blades, the HP stationary blades of HP turbine and the

front rows of LP turbine are designed with integrally milled inverted T-

roots and shrouds. The last stages of LP turbine have guide blade rows

of fabricated construction.


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Condensate

Steam after the extraction of work in the hp and lp turbines goes to

condenser through flash box where the LP drain enters the condenser.

Cooling water is supplied by the CW tubes where the water is pumped

in by CW pumps. Water generally gets heated by 7-8 degree celcius.

Steam from the LP exhaust gets condensed via indirect heating and is

collected below in the HOTWELL. Very low pressure in the condenser

is maintained by vacuum pumps. To make up for the water losses

during the steam cycle, make up water is added to the condenser via

DM water line. This DM water can be taken directly from the DM water

line or through the Reserve Feed Tank. Water from the Hotwell is

extracted by condensate extraction pumps (CEP). In this module two

CEPs are provided while only one is operated while other is kept in

standby mode. Water from the CEP discharge enters the Gland steam

condenser (GSC) where it is heated by the gland steam via indirect

heating. Gland steam condenses and is discharged back into the

condenser. Heated water from the GSC is then taken to LPH and other

feedwater systems.

Condenser also receives the HP and LP bypass lanes from the

turbines. The power-plant chemistry is constantly monitored via the

specific conductivity and the PH level of the water in the condenser.

Hotwell level is also important and is constantly controlled.


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Cooling water system

The water in the coolant tubes of the condenser gets heated and is

then taken to the cooling towers. Here the water gets sprinkled fromthe top of the specially designed cooling tower where the rising air

from the bottom cools the water close to its wet bulb temperature.

Thus temperature is lowered by 7-8 degree celcius. Unsaturated air of

low relative humidity gets saturated in this process and leaves the

cooling tower from the top. The suction of the air is provided by the

induced draft fans provided at the tower top. Thus cooling tower is

based on the forced draft cooling. Hence the height of the tower is

quite low.

Cooled water is discharged into the sump where the make up

water is added as water loss occurs during the cooling through

evaporation. Cooling water pumps get the suction from the sump and

pump the water towards the condenser.


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Feed water system

LP heater

Feed water from the GSC enters the LPH where the bled steam heats

the feed water by indirect heating .LPH bypass lane is also provided

to bypass the LP heater .

CPH and CPH RCP

The water from the LP heater goes to condensate preheater kept at

the near exhaust of the HRSG. The flue gases before being discharged

to the atmosphere are used to heat the feedwater. In this process the

temperature of the flue gases falls down from 160 to 104 degree

celcius. Generally this is above the saturation temperature of the SOX

and the NOX gases in the chimney exhaust. When the natural gas is

used the temperature is quite high and saturation temperature llimitis not reached however if the naptha is used then the flue gas

temperature is lower by around 10 degree celcius hence the NOX

gases could condense and form acidic products leading to cold end

corrosion, if the CPH is used. Hence to overcome this recirculation

pumps(RCPs) are switched on which pump the hot water at CPH

discharge back to the CPH inlet thus considerably reducing the heat

transfer and hence the flue gas temperature doesnt reduce to the

saturation temperature limit.

Deaerator

Water from the CPH heater enters the the deaerator where the

dissolved gases are removed from it. The steam from the LP

superheater enters the deaerator from the bottom while the

feedwater is sprinkled fron the top. The rising steam comes in direct

contact of water thereby heating the water and the dissolved gases

which as a result escape from the top along with some of the steam.

The condence steam and the water are collected below in the storage

tank. The storage tank is provided with the heating rod which is kept

hot by the lp steam. The storage tank then separately discharges the

feedwater to HP and LP BFP.

The deaerator is generally kept at the height of 20 to 25 meters to

keep the pressure head above the net positive suction head (NPSH)

level of the water at thr BFP suction.


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ELECTRICAL SYSTEMSELECTRICAL SYSTEMS

The major electrical components used in the switchyard are:


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ISOLATORS

Isolators (disconnecting switches) are switches, which operate

under no load conditions. They are used in addition to circuit

breakers and are provided on each side of circuit breaker to provide

isolation and enable maintenance.

While opening a circuit, circuit breaker is opened first and then theisolator. While closing a circuit, the isolator is closed first and then

the circuit breaker. Isolators are necessary on supply side of circuit

breaker to ensure isolation of circuit breaker from live parts for the

purpose of maintenance.

EARTHING SWITCH

Earthing switch is connected between line conductor and earth.Normally, it is open. When the line is disconnected, the earthing

switch is closed so as to discharge voltage trapped on the line.

Generally, earthing switches are mounted on the frame of the

isolators.

INSULATORS

Provision of adequate insulation in a sub-station layout is of primary

importance from the point of view of reliability of supply and safety

of personnel. The following are the considerations to be made:

The dielectric strength of the insulating material should be

high

It should possess high mechanical strength

It should posses high resistance to temperature changes

The leakage current (to the earth) should be minimum to keep

the corona loss and radio interference within reasonable limits

The insulator material should not be porous and should be free

from impurity and cracks.

The following are the insulators normally used:

Bus support insulator


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Solid core typePoly-cone typeCap and pin typeStrain insulatorsDisc insulatorsLong rod porcelain insulators

Polymer insulators

CARRIER EQUIPMENT

The carrier equipment required for communication, relaying andtelemeter is connected to the line through high frequency cable,coupling capacitor and the wave trap. The wave trap is normallyinstalled at the line entrance.

LIGHTNING ARRESTORSA sub-station has to be shielded against direct lightning strokes byprovision of overhead shield wire/earth wire or spikes (masts).Besides direct strokes, the equipments should be protected againsttravelling waves due to lightning strokes on the lines entering thesub-station. This is done by lightning arrestor.

The most important and costly equipment in a sub-station is the

transformer and the normal practice is to install lightning arrestors as

near to the transformer as possible. Besides protecting the

transformer, the lightning arrestor also provides protection to the

equipment on the bus side located within certain distances

Transformer

Transformer is an ac machine that (i) transfer electrical energy

from one electric ckt to another (ii) does so without a change of

frequency (iii) does so by the principal of electro-magnetic induction

and electric ckt that are linked by a common magnetic ckt.

Operating principal


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The action of transformer is based on the principal

that energy may be efficiently transferred by induction from one set of

coil to another by means of varying magnetic flux

Emf equation

Rms value of emf induced = EMF induced per

turn* no of turn

=4.44*N*f*(flux)

Transformer construction

The transformer is very simple in construction and consists of

magnetic ckt linking with two winding .it consist of a suitable

container for assemble core and winding, such as a tank, a suitable

medium for insulation from it container such as transformer oil, a

suitable bushing for insulating and bringing out terminal of the

winding from the container .etc..

Following main part in the transformer construction;

1. Core construction ;

A transformer core is the steel system which

forms the magnetic with all part pertaining to its construction.

Those part of magnetic ckt which carry the transformer winding

are called the limbs or legs. The core material and construction

should be such that maximum flux is created with minimum

magnetizing current and minimum core loss. The magnetic frame of

the transformer is built up of laminated electro-technic steel. Its

called transformer grade steel consist of 3.5% silicon.

2. Insulation;


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Insulation used in transformer may be classified into two major group

viz major insulation and minor insulation. Major insulation between

winding usually consist of sheet of pressboard and oil ducts. And

minor insulation include the insulation provided between the element

of a given winding such as conductor insulation, insulation betweenthe turns, layers and coil.

3. Insulation oil;

The insulation oil has provides additional insulation ,

protect the insulation from and moisture and it carries heat away the

heat generated in core and coil .

4. Tank;

Small capacity tank are fabricated from welded sheet steel,

while larger one are assembled from plain boiler plates or cast

aluminium parts.

5. Temperature gauge;

Every transformer is provided with a temperature gauge

to indicate hot oil or hottest spot temperature it is a self contained

weatherproof unit made with alarm contact.

7. Oil gange;

Every transformer is provided with an oil gange to indicate

the oil level

8. Breather;


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When the transformer become warm, the oil and gas

expand. The gas at the top of the oil is expelled out .when the

transformer cools, air is drawn into the transformer. Unless preventive

measure are taken, moisture is drawn during the process and it call

breathing.

9. Gas operated relay Buchholz relay;

It is gas and oil actuated protective device and its

practically universally used on all oil immersed transformer having

rating more than 750 kva. The use of such relay is possible only

transformer having conservator.

10.Bushing;

Transformer are connected to hv lines and therefore it

care is to be taken to prevent flash-over from the high voltage

connection to earthed tank. Connection from cable are made in cable

boxes. But overhead connection are to be brought through bushingspecial designed for different classes of voltage.

Type of transformer

Depending upon the type of construction:

1. Core type
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2. Shell type

Depending upon the type of service, in the field of powersystem:

1. Power transformer

2. Distribution transformer

1. Power transformer;

The term is used to include all transformer of

large scale used in generating station and substation for transforming

the voltage at each end of a power transmission line.
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2. Distribution transformer;

The transformer f rating upto 200 kva, used

to step down the distribution voltage to a standard service voltage are

know as distribution transformer.

Generator

Generator is one of the important type of electric machines.

Large ac network operating at constant frequency of 50 hz its called

synchronous generator or alternator

Operation principal;

The operation principal of generator fundamentally same as the dc

machine. But in generator there is no need rectify the time varying

emf which induced in the armature windingit dont required a

commutator. Synchronous generator because of absence of

commutator are comparatively simple and possess several importantadvantage over the dc generator

Generator is a synchronous generator which receives mechanical

energy from a prime mover to which it is mechanical coupled and

drivers electrical energy. Its may be single, two or 3-phase

It classified as i)rotating armature type ii)rotating field type


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Mechanical systemsGas Turbine & Auxiliaries

The plant has two Gas Turbines of Siemens AG model type V94.2,

supplied by BHEL. One Gas Turbine was manufactured at Siemens AG,

Germany and the second Gas turbine has been manufactured by

BHEL. The Gas Turbine is a single shaft machine of single casing

design. Net Output of the Gas Turbine in Open cycle at guaranteed

conditions is 143.22 MW. Peak output is 150.51 MW. ISO output of the


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machine is 159.8 MW. Compression ratio and Turbine Inlet

temperature are 10.5 and 1060 C respectively.

Gas Turbine GUARANTED VALUES

Type V 94.2

Fuel NATURAL GAS

Lower Calorific Value KJ/KG Base Load Peak

load

Net Power Output MW 143.220 150.510

Nox Emissions PPM (V) 50

Reference

Speed RPM 3000

Ambient temperature 0C 27

Barometric pressure bar 1.013

Relative Humidity % 60

Generator power factory -------- Lagging 0.85

Generator Type TARI:108/41

Technical Data sheet-Gas Turbine V94.2

1. Gas Turbine

i. Type / Model V94.2

ii. Manufacture BHEL/SIEMENS

iii. Firing Fuels Natural Gas Main

(Naphtha Alternate HSD Start up/Shut down)

2. Compressor

Type Axial flow Heavy duty

No. of stage 16

Rated quantity of air flow 510 ISO (Kg/sec)


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Compressor ratio 11:1 (ISO Firing NG)

Type of fixing of rotor discs Hirth serration splined together by Tie

Rod

Protective coating for compressor blades Sermetal

No. of coated stationary blade rows 3+ Inlet Guide Vane

No. of coated moving blade rows 6

3. Combustion System

Type Silo Type

No. of combustion Chamber 2

No. of burner / combustion chamber 8

Type of burners Hybrid Burner

Fuel Pressure requirement NG17.5 to 22 bar, oil approx.

80bar at combustion Inlet

(Kg / cm2)

Nox level generator


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The gas turbines are equipped with water injection arrangement. DMwater shall be injected in the combustion chamber to reduce theflame temperature and thereby reduce the NOx emission level duringfuel oil operation. There are 2x100% water injection pumps for each ofthe two gas turbines. The maximum quantity of water injection is 48ton per hour for one gas turbine at maximum gas turbine out put

condition. The system is designed to achieve 65 ppm of NON, duringHSD or Naphtha operation.The NOX Water Injection System details are as given below:

De- NOX Water Injection PumpMake KSB PUMPS LTD.Capacity 50.4 CuM/hrHead 402 M

MotorMake SIEMENSVoltage 415 V, 50 Hz, 3 PHRating 90 KWCurrent 150 A

Heat Recovery Steam Generator (HRSG)

Two Heat Recovery Steam Generators (HRSG) are installeddownstream of two Gas Turbines. HRSGs are unfired water tube, dualpressure, natural circulation type with staggered tube pitcharrangement. These are BHELs Module Steam Generators (MSG)designed for extensivq shop fabrication in order to minimize fieldinstallation cost and schedule.

The system details of HRSG are as given below:

Type OF WHRB Horizontal/ Natural Circulation

HP LPRated Flow T/Hr 231.131 46.383Rated Press.Ksc 81 4.7Rated Temp.deg 530 200

OUT LINE DIMENSIONS

Length 56 M Up to Chimney Center LineHeight 27.4 M Drum Center Line

Width 19.5 M

HP SUPER HEATER AND COMPONENTS


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Design Pressure 106 KscDesign Temperature 569 degGas Flow path Area 76.8 Sq. mDepth of each bank Limited to 1800 mmIn the direction of gas flow

Max. metal temperature 541 deg

HP Main Steam Line

--Pipe Size mm x mm 406.4 x 65--Material SA 335 P 22

LP SUPER HEATER AND COMPONENTS

LP Main Steam Line

--Pipe Size mm x mm 406.4 x12.5--Material SA 106 Gr. B

HP EVAPORATOR AND COMPONENTS- CIRCULATION SYSTEM

Total Heating Surface Area(sqm)-- Gas Side 43929-- Water/ Steam Side 3427

Total No. of Tubes in the bank 1200

-- No. of rows with flow direction 20-- No. of tubes per row 60

Tube Arrangement Staggered

Tube outer diameter mm 51.0

LP EVAPORATOR AND COMPONENTS- CIRCULATION SYSTEM

Total Heating Surface Area (Sq. m)-- Gas Side 31211-- Water/ Steam Side 2399

Total No. of Tubes in the bank 840


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-- No. of rows with flow direction 14-- No. of tubes per row 60

Tube Arrangement StaggeredTube outer diameter mm 51.0Tube Thickness mm 3.0

HP ECONOMISER AND COMPONENTS

Total Heating Sq. mSurface Area-- Gas Side 28956-- Water Side 3096Total No. of tubes in the bank 1520-- No. of rows with flow direction 19-- No. of tubes per row 80

Tube Arrangement StaggeredTube Outer diameter mm 38.1Tube Thickness mm 3.6

LP ECONOMISER AND COMPONENTS

Total Heating Sq. m 368Tube Arrangement Staggered

Tube Outer diameter mm 51Tube Thickness mm 3.0

CONDENSATE PRE HEATER

Total Heating Sq. mSurface Area--Gas Side 24385--Water Side 2607

Total No. of tubes in the bank 1280-- No. of rows with flow direction 16-- No. of tubes per row 80

Tube Arrangement StaggeredTube Outer diameter mm 38.1Tube Thickness mm 3.0

Steam Turbine & Auxiliaries

There is one steam turbine generator set capable of accepting theentire steam generated by two heat recovery steam generators of the


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module. Gross output of Steam Turbine at Generator terminals atdesign operating conditions is 159.99 MW. The steam turbine is ofBHEL make, tandem-compound, condensing, double exhaust havingone single flow HP cylinder and one double flow LP cylinder withreaction type bladeing. HPT module is M-30-25 and LPT. module is N-30-2x HP turbine has 25 stages and LP turbine has 2X7 stages. The

turbine is throttle governed and is capable of accepting variationsfrom the rated conditions within the limits as recommended by IEC-45.The turbine can be operated continuously within the frequency rangeof 47.5 to 51.5 Hz.

The details of Steam Turbine are as given below:

SL. STEAM TURBINE DESCRIPTION

1. Make BHEL

2. Rated output 156 MW

3. Rated steam pressure 78 Kg/sq. cm

4. Rated steam temperature 528 oC

5. Overall length 134.4m (approx.)

6. Overall height 12.0 m (approx.)

7. Type of blading REACTION

8. Type of governing THROTTLE

9. Module No. & details

(i) HP M-30-25 (SINGLE FLOW)

(ii) LP N-30-2X5 (DOUBLE

FLOW)

Rated Condenser Vacuum(mm of Hg) 0.101 Bar

Rated CW Inlet Temp.0C 32

10. Type of cylinders

HP cylinder SINGLE FLOW/

HORIZONTAL SPLIT

LP cylinder DOUBLW FLOW/


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HORIZONTAL SPLIT

11.Operation Frequency

Range

Operation Regime

a) Continuous Operationb) Limited Operationrange continuous at astretch & total lifetime

c) Speed exclusion rangeat operation withoutload

d) Standard over speedtrip setting

Frequency Range

47.5 Hz to 51.5 Hz

Permissible for a

maximum 2 hrs during

the life of LP Blading

speed below 47.5 Hz

speed above 51.5 Hz.

11.7 to 47.5/s

55.5/s

12. Turbine rated speed

(RPM)

3000

13. (i) Critical speeds for

turbine (RPM) balded

rotors

HP 3812

(ii) Combined critical speeds

(RPM) of TG set

1527, 1814, 4187,

5017, 2120.

14. Type of turbine gear HYDRAULIC

15. Turbine speed 50-60 rpm

18. Turbine Governing system

(i) Type ELECTRO HYDRAULIC

(ii) Make BHEL

16. Mode of governing THROTTLE

17. Casing Details

HPT Casing

a) Typeb) No. of Casingsc) No. of No. of flowsd) Inlet parameters

Split

Two


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i) Pr. Kg/cm2

ii) Temperature 0C

e) Exhaust Parameteri) Pr. Kg/cm2

ii) Temperature0

C

Single

--

76.4

528.5

51

175

LPT Turbine

a) Type

b) No. of Casings

a) No. of No. of flowsb) Inlet parameters

Pr. Kg/cm2

ii) Temperature 0C

c) Exhaust ParameterPr. Kg/cm2

Temperature 0C

Split

Two

Single

--

48.3

200

0.105

46.1

Shaft Seal Assembly and Seal Steam System

The external shaft seals at the rotor ends of steam turbine prevent

the ingress of air through any of the shaft seals and discharge of

steam to atmosphere. They perform these functions in conjunction

with the shaft seal steam supply system. HP rear end and LP front

and rear shaft seals are See through type. The advantage of this

type of seal is that it is possible to optimize spacings between theseal strips regardless of relative expansions between rotor and


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housing. HP front end has labyrinth type seals. Seal steam from LP

steam lines of the HRSGs, is fed to seals through a self contained

hydraulic actuated pressure control valve during startup and low

load operation. At higher load leak-off from HP turbine glands

supplies sealing steam through a pressure control valve similar to

seal steam control valve. 2x100% seal steam exhauster fans extract

steam-air mixture from turbine glands to maintain slight vacuum

avoiding steam leakage to atmosphere.

Gland Steam Exhauster

i) Number of pumps in

service (No.)

ONE (1) + One (1)

Stand By

ii) Make & type SK Systems Pvt Ltd.

iii)Size 12.5 x C1

iv)Speed (RPM) 2840

v) Motor rating (kw) 2.2

Condenser

The condenser is box type construction with divided water box, twopass, spring supported, and welded with exhaust-hood of the LP

turbine. The condenser is designed for a heat load of 274.1135 X 106

Kcal/hr, and design circulating water quantity is 26800 m3 per hour.

Temperature rise of cooling water at design point is 10.220 C. The

condenser is provided with integral aircooling section where air and

non-condensable gases are drawn out with help air evacuation

equipment. The condenser is fitted with welded Stainless steel tubes

(grade SS TP 304). Water boxes are dome shaped removable typeand are provided with necessary hinged manholes for easy access to

the interior for inspection. 2x100% vacuum pumps are provided for

maintaining the vacuum in condenser. The vacuum pumps are of

liquid ring type with rotor eccentric to the casing. Pumps are

designed for hogging as well as holding operation. During hogging

operation, both pumps will work simultaneously for quick evacuation,

while during holding operation one pump will operate.


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Main Steam System

The steam generated by individual HRSG is discharged into separate

HP and LP headers. Both HP and LP steam lines are provided with

following features:

i) Motorised steam isolation valves in individual steam lines from

each HRSG near the common steam header going to the steamturbine.

ii) Motorised steam stop valves near each FIRSG to facilitate the

maintenance of individual HRSG and carryout the hydraulic test etc.

iii) Individual bypass lines from individual HPILP steam lines from

HRSG upstream of motorised steam isolation valve.

iv) Suitable warm up arrangement for HP steam lines.

The steam for deaerator pegging is tapped off from the individual

steam lines with two motorised isolation valves. These are joined

together and a common line is run up to the deaerator. Sealing

steam for steam turbine is also taken from this header.

STEAM PRESSURES

Rated Long-time

Operation

Shorttime

Operation

Initial steam 76.04 87.9 99.4 Bar

Ahead of Ist HP drum stage 74.9 86.1 86.1 Bar

At Ist cylinder exhaust 5.1 5.9 5.9 Bar

At inlet to induction stem

valve

5.6 6.4 12 Bar

At inlet to second cylinder 4.83 5.6 5.6 Bar

At second cylinder exhaust 0.101

5

0.3 0.3 Bar

Short time operation: Permissible momentary value. The aggregate

duration of such swings must not exceed 12 hours in any one year


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STEAM TEMPERATURES

Read value

Annual

mean

value

Long-time

value but

keeping

withinannual

mean value

400 h

per

annum

40 h per annum max.

15 min in individual

case

Initial

steam

528.2 531.6 542.2 556.1 0C

At inlet to

LP steam

valve

200.0 208.0 214.0 228.0 0C

At 1st

cylinder

exhaust

175.0 200.9 212.9 340 0C

At 2nd

cylinder

inlet

181.8 207.7 221.7 228.0 0C

At 2ndcylinder

exhaust

46.1 70 70

Condensate System

, 2100%

() .

700 3/ 225 .

().

.

,

.

,


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.

.

() . 350%

,

. .

.

.

,

. ,

2100% , .

Feed Water System

Water from deaerator feed storage tank is fed to HP Economiser and

LP Economiser circuits of the two HRSGs by means of HP and LP

feed water pumps (each 3x50%). Six separate outlet connections are

provided from the deaerator for suction of the pumps. Design rating

of each HP Feed Pump is 325 m3/hour and 1500 MLC. HP Feed water

pumps are high pressure, multistage, horizontal, barrel casing,

removable cartridge type rotating elements, centrifugal pumps.

Single stage Booster pump ensures that NPSH requirements of HP

Feed pumps are met in all operating conditions. A common motor

drives both booster pump and Feed pump through a constant speed

mechanical gearbox. Design rating of each LP Feed Pump is 67

m3/hour and 172 MLC. LP BFPs are also horizontal multistage type

centrifugal pumps, with Ring section design. Both HP and LP Feed

Pumps are provided with minimum re-circulation lines from the

discharge of each pump, for maintaining the minimum flow

requirement of each pump. The minimum recirculation lines are

connected back to feed storage tank.

HP BOILER FEED PUMP


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GENERALDesignation HP Boiler Feed PumpNo. of Pumps 3x 50%Type of Operation ContinuousType of pumps` FK 6D 30Type of Drive Motor

DESIGN PARAMETERSLiquid handled Feed waterTemp of feed water, 0C 155.7Specific weight of feed 911.2Water kg/m3

Suction flow, m3 /hr 325Dynamic Head, mlc 1404Speed, rpm 4200Power input to pump, KW 1400Efficiency of pump,% 81

LP BOILER FEED PUMP

Make Kirloskar EBARA Pumps LtdType 100 x 80 MSS4MCapacity 66.4 CuM/ HrHead 180 M

MOTOR

Make Kirloskar Electric Co.

Control and instrumentation

In the FGPS, application of instrumentation and control systems arefor centralized, automated and safe plant control of equipments likegas turbines, heat recovery steam generators (HRSG), steam turbine

generator and their auxiliaries to achieve maximum efficiency,reliability, safety and availability. There is optimum plant control dueto these controlled instrumentation and control system. In the plant,C&I systems are microprocessor based with functionally distributedpanels i.e. for different signals there are different microprocessorsbased input output cards.

Instrumentation and control panels are provided for each gas turbine

generator and steam generator.


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THE MAJOR COMPONENTS IN THE SYSTEM INCLUDE THE

FOLLOWING

The analog control system

The binary logic control system

The data acquisition and processing system

The power supply system

The operation of the power plant is controlled from the central control

room in which the control panels are located. Provision is made for

local starting and testing of the important equipments, pumps and

motors.

The control panels accommodate keyboards for CRTs, Auto-Manualsstations, set-point stations, sequential control modules, push button modules,

selector switches, emergency shutdown devices, etc.

Protection


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Chemical analysis/water treatment analysis

A large quantity of water is used in boiler for generation the steam.The water used in boiler is called boiler feed water. Hard watercreates a number of problems like corrosion, scale and sludgeformation etc. Natural water is not directly used in boiler because itcontains hardness producing salts. Hence water should be properlysoftened and pure before feeding into boiler.

To softened and pure water following methods:

*By removal of dissolved oxygen& CO2

---- by mechanical deaeration method

*By adding of alkali

Mechanical deaeration method used in NTPC for purification water


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REPORT Electrical

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