Chapter-1

INTRODUCTION

National Thermal Power Corporation Ltd (NTPC) was incorporated in 1975 by an Act of

parliament, to supplement the efforts of the states for quicker and greater capacity addition

in thermal power generation .In1997 the Department of Public enterprises, Government of

india status with power of operational autonomy to the board of NTPC . This helped NTPC

in speedy implementation of power projects. Recently NTPC has been awarded the

Maharatna status which has given it greater autonomy.

In line with its vision and mission over the last five years NTPC has grown

to become the largest power utility in India with a commission degeneration capacity of

34,754MW (asonJuly,2011) .Besides largest power generation utility NTPC has also grown

to become the number one independent power in Asia and second globally in 2009 (by Platt

a division of McGraw-Hill companies) ,5largest company in Asia and 317Largest company

in the world (FORBESranking–2009) .NTPC has also thehonor of becoming the 6th

largest

the power generator in the world and second most efficient in terms of capacity utilization

among stop 10 utilities in the world.

In line with the changing business environment ,NTPC has expanded its

operation in the area of Hydro Power and cover substantial ground in the area sof Coal and

Mining .Oil& Gas Value chain ,Power Trading and Distribution .With the forward and

backward plans ,NTPC has been re-christened as “NTPC Limited“ since 7th

Nov2005.

1

Chapter-2

NTPC MISSION AND VISION

NTPC ultimately produce and deliver quality power in optimum cost and eco-friendly

manner through concerted team effort sand effective system. Being an PSU,An has

derivedits mission an dvision aliging with that of the Corporate Mission and Vision.

2.1 GAS STATION

Table 2.1 Gas

Station

2.2 ANTA GAS POWER STATION

Rapid industrialization and growth in agriculture/domestic consumption of power in the North

India was putting lot of strain on the power grid .To overcome the gap between supply and

demand NTPC setup its first Gas Power Station at Anta .Presently NTPC ,Anta is one of the

seven Gas station of NTPC. Anta project was setup to mitigate the power short again the

Northen region which was estimated between 13-16% of the peak demand during the7th

plan

period.

2

GAS BASED STATE COMMISSI

ONEDCAPA

1. Anta Rajasthan 413

2. Auriya UttarPradesh 652

3. Kawas Gujarat 645

4. Dadri UttarPradesh 817

5. Jhanor- Gandhar Gujarat 648

6. Rajiv

GandhiOCPPk

Kerala 350

7. Fridabad Haryana 430

Total 3,955

2.3 SAILENT FEATURES OF NTPC ANTA

1. Station : Combined Cycle Gas Based Power Station

2. Gas Turbine : 3x 88.71MW

3. Steam Turbine : 1x 153.2MW

4. Total Capacity : 419.33 MW

5. Gas turbine : 88MW,Type ABB Gas turbine,5 Stage

6. GT Comprossor : 18 stage Axial flow (typeVA14018)

7. Combustion Chamber : Single Silotype

3

Chapter-3

POWER GENRATION PROCESS

The Gas/Naphtha from pipeline is taken and supplied to GT Combustion chamber where it is

burn as fuel along with air drawn from atmosphere. This heat is then convert into mechanical

energy in the Gas Turbine. Gas turbine through a common shaft rotates Generator, which

produces electric power. Flue gas from the turbine exhaust is used to convert water into steam

in the Waste Heat Recovery Boiler (WHRB).Water required for steam generation is circulated

through the tube sin the boiler, where heat exchange takes place and water gets converted in

to steam. The steam generated from WHRB is used to run a steam turbo generator and

produce electric power. This power is supplied to customer through 220KV lines.

Figure 3.1 Process Of Power Generation

4

3.1 OVER VIEW OF COMBINED CYCLE

Combined cycle power plant integrates two power conversion cycles with the principal

objective of increasing overall plant efficiency.

1. Bratyon cycle (for gas turbine)

2. Rankine cycle (for steam turbine)

3.1.1 How Combined Cycle Works In Combined Cycle Power Plant

Gas turbine exhaust is at temperature of500-550Celcius

Steam generation process for Rankine cycle requires a temperature of500-550Celcius

to generate steam.

Gas turbine exhaust heat can be recovered using a waste heat recovery boiler to

generate steam in a water tube boiler so as a steam turbine on Rankine cycle.

Efficiency of simple gas turbine cycle is 34%.

The efficiency of Rankine cycle is 35%.

The overall efficiency of power generation by combined cycle comes to 49%.

3.2 STEAM TURBINE

Steam Turbine is a heat engine, working On Rankine cycle .The

process includes

1. Heating: Phase change of working medium (from water to steam) and super heating at

constant pressure in Boiler.

2.Expansion: Expansion of the steam in a turbine

3. Pressurization: Pressurization of working medium(water)by boiler feed water pump.

5

Figure 3.2 Steam Turbine Floor

A steam turbine is a prime mover in which rotary motion is obtained by gradual change of

momentum of the steam. In a steam turbine, the force exerted on the blades is due the

velocity of steam. This is due to the fact that the curved blades by changing the direction of

steam receive a force or impulse. The dynamical pressure of steam rotates the blades

directly. The turbine blades are curved in such a way that steam directed upon them enters

without shock. The steam turbine essentially consists of following two parts. The nozzle in

which the heat energy of high pressure steam is converted into K.E.so that the steam issues

from the nozzle with a very high velocity .The blade which changes the direction of steam.

6

Chapter-4

GAS TURBINE

Gas turbine is a heat engine working on the air standard Brayton cycle.

The process Includes

1. Compression: Compression of working medium (air) taken from atmosphere in a

compressor.

2. Combustion: Increase of working medium temperature by constant ignition of fuel

in combustion chamber.

3. Expansion: Expansion of the product of combustion in a turbine.

4. Rejection: Rejection of heat in the atmosphere.

4.1 OVER VIEW OF GAS TURBINE

1. Air intake system

2. Compressor

3. Combustion Chamber

4. Turbine

5. Generator

6. Gas Fuel System

7. Naphtha Fuel system

7

8

4.2 MAJOR COMPONENTS OF GAS TURBINE

1. IN LET AIR

2. COMPRESSOR

3. TURBINE

4. COMBUSTION SYSTEM

5. EXHAUST

6. BASIC GT ASSEMBLY

Figure4.1GasTurbine

9

Chapter-5

FIELD INSTRUMENTS

1. PRESSURE GAUGE

2. TEMPERATURE GAUGE

3. PRESSURE TRANSMITTER

4. TEMPERATURE TRANSMITTER

5. DP TRANSMITTER

6. VIBRATION PICK UP

7. SPEED PICK UP

8. FLOW SENSOR

9. LEVEL SENSOR

10. PRESSURE SWITCH

11. THERMOCOUPLE ,RTD

Figure 5.1 Work Flow Diagram

10

5.1 PRESSURE TRANSMITTER

Capacitance type pressure transmitter Diaphragm acts a plate of capacitor which moves w.r.t

fixed plate causing change in capacitance which is converted & amplified into a DC 4-20mA

signal. This operates on two wire.

Figure 5.2 Pressure Transmitter

11

5.2 TEMPERATURE GAUGE

Temperature Gauge is used to measure the temperature of device.

Figure 5.3. Temperature Gauge

12

5.3 FLOW MEASUREMENT

5.3.1 Differential Pressure Flow meters

The basic operating principle :

The pressure drop across the meter is proportional to the square of the flow rate.

The flow rate is obtained by measuring the pressure differential and extracting the

square root

Different pressure flowmeter are:-

1. ORIFICE

2. VENTURI

3. NOZZLE

4. PITOT TUBE

5.3.2 Electromagnetic Flow Meter

When a liquid conductor moves in a pipe having a diameter (D) and travels with an average

velocity (V) through a magnetic field of B intensity, it will induce a voltage (E) according to

the relationship:

E = C B D V

5.4 LEVEL MEASUREMENT

1.Differential Pressure transmitter

Level is measured through Electronic DP transmitter

2. Ultrasonic level transmitter

Level is measured by ultrasonic transmitter mounted on the top of the tank

3. Guided wave radar type level transmitter

13

Generally used for low pressure app

4. Hydra step

Most commonly used for Boiler drum measurement.

5.5 THERMOCOUPLE

It is based on SEEBACK effect which says that when heat is applied to a junction of two

dissimilar metals an EMF is generated which can be measured at the other junction.

Figure 5.4. Thermocouple

Thermocouple translate the temperature into Voltage which is then measured and processed

to compute numerical Value of temperaturewhen two wires of electrical properties are joined

together at the both end one junction made hot& other junction made cold small electrical current

produced proportional to the difference in the temperature.

14

Chapter-6

GENERATOR

The transformation of mechanical energy into electrical energy is carried out by the

Generator. This Chapter seeks to provide basic understanding about the working principle

and development of Generator.

6.1 WORKING PRINCIPLE

The A.C. Generator or alternator is based upon the principle of electromagnetic induction and

consists generally of a stationary part called stator and a rotating part called rotor. The stator

housed the armature windings. The rotor houses the field windings. D.C. voltage is applied to

the field windings through slip rings. When the rotor is rotated, the lines of magnetic flux (i.e.

magnetic field) cut through the stator windings. This induces an electromagnetic force (EMF)

in the stator windings. The magnitude of this EMF is given by the following expression.

E = 4.44 /O FN volts

0 = Strength of magnetic field in Weber’s.

F = Frequency in cycles per second or Hertz.

N = Number of turns in a coil of stator winding

F = Frequency = P*n/120

Where P = Number of poles

n = revolutions per second of rotor.

From the expression it is clear that for the same frequency, number of poles increases with

decrease in speed and vice versa. Therefore, low speed hydro turbine drives generators have

14 to 20 poles were as high speed steam turbine driven generators have generally 2 poles.

6.2 GENERATOR COMPONENT

This deals with the two main components of the Generator viz. Rotor, its winding &

balancing and stator, its frame, core & windings.

15

Rotor

The electrical rotor is the most difficult part of the generator to design. It revolves in most

modern generators at a speed of 3,000 revolutions per minute. The problem of guaranteeing

the dynamic strength and operating stability of such a rotor is complicated by the fact that a

massive non-uniform shaft subjected to a multiplicity of differential stresses must operate in

oil lubricated sleeve bearings supported by a structure mounted on foundations all of which

possess complex dynamic be behavior peculiar to them. It is also an electromagnet and to

give it the necessary magnetic strength.

The windings must carry a fairly high current. The passage of the current through the

windings generates heat but the temperature must not be allowed to become so high,

otherwise difficulties will be experienced with insulation. To keep the temperature down, the

cross section of the conductor could not be increased but this would introduce another

problems. In order to make room for the large conductors, body and this would cause

mechanical weakness. The problem is really to get the maximum amount of copper into the

windings without reducing the mechanical strength. With good design and great care in

construction this can be achieved. The rotor is a cast steel ingot, and it is further forged and

machined. Very often a hole is bored through the centre of the rotor axially from one end of

the other for inspection. Slots are then machined for windings and ventilation.

Rotor winding

Silver bearing copper is used for the winding with mica as the insulation between conductors.

A mechanically strong insulator such as micanite is used for lining the slots. Later designs of

windings for large rotor incorporate combination of hollow conductors with slots or holes

arranged to provide for circulation of the cooling gas through the actual conductors. When

rotating at high speed. Centrifugal force tries to lift the windings out of the slots and they are

contained by wedges. The end rings are secured to a turned recess in the rotor body, by

shrinking or screwing and supported at the other end by fittings carried by the rotor body.

The two ends of windings are connected to slip rings, usually made of forged steel, and

mounted on insulated sleeves.

16

Rotor balancing

When completed the rotor must be tested for mechanical balance, which means that a check

is made to see if it will run up to normal speed without vibration. To do this it would have to

be uniform about its central axis and it is most unlikely that this will be so to the degree

necessary for perfect balance. Arrangements are therefore made in all designs to fix

adjustable balance weights around the circumference at each end.

Stator

Stator frame: The stator is the heaviest load to be transported. The major part of this load is

the stator core. This comprises an inner frame and outer frame. The outer frame is a rigid

fabricated structure of welded steel plates, within this shell is a fixed cage of girder built

circular and axial ribs. The ribs divide the yoke in the compartments through which hydrogen

flows into radial ducts in the stator core and circulate through the gas coolers housed in the

frame. The inner cage is usually fixed in to the yoke by an arrangement of springs to dampen

the double frequency vibrations inherent in 2 pole generators. The end shields of hydrogen

cooled generators must be strong enough to carry shaft seals. In large generators the frame is

constructed as two separate parts. The fabricated inner cage is inserted in the outer frame

after the stator core has been constructed and the winding completed. Stator core: The stator

core is built up from a large number of 'punching" or sections of thin steel plates. The use of

cold rolled grain-oriented steel can contribute to reduction in the weight of stator core for two

main reasons:

a) There is an increase in core stacking factor with improvement in lamination cold Rolling

and in cold buildings techniques.

b) The advantage can be taken of the high magnetic permeance of grain-oriented steels of

work the stator core at comparatively high magnetic saturation without fear or excessive iron

loss of two heavy a demand for excitation ampere turns from the generator rotor.

Stator Windings

Each stator conductor must be capable of carrying the rated current without overheating. The

insulation must be sufficient to prevent leakage currents flowing between the phases to earth.

Windings for the stator are made up from copper strips wound with insulated tape which is

17

impregnated with varnish, dried under vacuum and hot pressed to form a solid insulation bar.

These bars are then place in the stator slots and held in with wedges to form the complete

winding which is connected together at each end of the core forming the end turns. These end

turns are rigidly braced and packed with blocks of insulation material to withstand the heavy

forces which might result from a short circuit or other fault conditions. The generator

terminals are usually arranged below the stator. On recent generators (210 MW) the windings

are made up from copper tubes instead of strips through which water is circulated for cooling

purposes. The water is fed to the windings through plastic tubes.

6.3 GENERATOR COOLING SYSTEM

The 200/210 MW Generator is provided with an efficient cooling system to avoid excessive

heating and consequent wear and tear of its main components during operation. This Chapter

deals with the rotor-hydrogen cooling system and stator water cooling system along with the

shaft sealing and bearing cooling systems.

Rotor Cooling System

The rotor is cooled by means of gap pick-up cooling, wherein the hydrogen gas in the air gap

is sucked through the scoops on the rotor wedges and is directed to flow along the ventilating

canals milled on the sides of the rotor coil, to the bottom of the slot where it takes a turn and

comes out on the similar canal milled on the other side of the rotor coil to the hot zone of the

rotor. Due to the rotation of the rotor, a positive suction as well as discharge is created due to

which a certain quantity of gas flows and cools the rotor. This method of cooling gives

uniform distribution of temperature. Also, this method has an inherent advantage of

eliminating the deformation of copper due to varying temperatures.

Hydrogen Cooling System

Hydrogen is used as a cooling medium in large capacity generator in view of its high heat

carrying capacity and low density. But in view of it’s forming an explosive mixture with

oxygen, proper arrangement for filling, purging and maintaining its purity inside the

generator have to be made. Also, in order to prevent escape of hydrogen from the generator

casing, shaft sealing system is used to provide oil sealing.

The hydrogen cooling system mainly comprises of a gas control stand, a drier, an

18

liquid level indicator, hydrogen control panel, gas purity measuring and indicating

instruments.

The system is capable of performing the following functions:

I. Filling in and purging of hydrogen safely without bringing in contact with air.

II. Maintaining the gas pressure inside the machine at the desired value at all the times.

III. Provide indication to the operator about the condition of the gas inside the machine

i.e. its pressure, temperature and purity.

IV. Continuous circulation of gas inside the machine through a drier in order to remove

any water vapor that may be present in it.

Stator Cooling System

The stator winding is cooled by distillate. Turbo generators require water cooling

arrangement over and above the usual hydrogen cooling arrangement. The stator winding is

cooled in this system by circulating demineralised water (DM water) through hollow

conductors. The cooling water used for cooling stator winding calls for the use of very high

quality of cooling water. For this purpose DM water of proper specific resistance is selected.

Generator is to be loaded within a very short period if the specific resistance of the cooling

DM water goes beyond certain preset values. The system is designed to maintain a constant

rate of cooling water flow to the stator winding at a nominal inlet water temperature of 400C.

6.4 RATING OF 95 MW GENERATOR

Manufacture by Bharat heavy electrical Limited (BHEL)

1. Capacity - 117500 KVA

2. Voltage - 10500V

3. Speed - 3000 rpm

4. Hydrogen - 2.5 Kg/cm2

5. Power factor - 0.85 (lagging)

19

Chapter-7

CONTROL AND INSTRUMENTATION

This division is basically brain of the power plant and this division is responsible for:

1. Is responsible for protection of boiler turbine & generator & associated auxiliaries.

2. It is responsible for display of all the parameters to the operator for taking the manual

action in case of emergency.

3. Responsible for logging of sequence of events taking place in the control room.This

department is the brain of the plant because from the relays to transmitters followed

by the electronic computation chipsets and recorders and lastly the controlling

circuitry, all fall under this.

4. This division also calibrates various instruments and takes care of any faults occurring

in any of the auxiliaries in the plant provided for all the equipments. Tripping can be

considered as the series of instructions connected through OR GATE. When the main

equipments of this laboratories are relay and circuit breakers.

Figure7.1ControlUnit

20

Chapter-8

TRANSFORMER

8.1 INTRODUCTION

A transformer generally consist of one or more coils (windings) of conducting wire, wound

on a former (bobbin) that surrounds the centre limb (sometimes all limbs) of a circuit of

magnetic material (core). The winding wires are insulated and the core is made from thin

sheet steel plates known as laminations (this reduce ‘eddy current’ losses). The assembly is

held together by metal cheeks known as clamps, these clamps are held in place by long

screws that are insulated from the rest of the structure (again to limit eddy currents). The

winding wires are either made off to terminals mounted on the clamps or the wire may leave

the coil by ‘flying leads’.

Figure 8.1 :- Transformer

Common types of laminations are shown above, they are known by the shape of letter that

they from. The most common type is the ‘E’ & ‘I’ from, the ‘T’ & ‘U’ is still used, but was

more common in days past. The laminations are often oxidized to form a surface film of

oxide that has a higher resistance than plain steel, thus isolating each layer to a certain extent

21

and reducing eddy current that may occur perpendicular to the plane of lamination.

Sometimes one or both sides of a lamination are sprayed with lacquer for insulation purposes.

Laminations are mostly at power distribution frequencies of 50 Hz or 60 Hz and audio

frequencies; if higher frequencies (up to a hundred or so kHz) are envisaged then ferrite or

other sintered iron oxide compounds are used to make solid split cores. Commonly used

versions are RM Cores and ETD cores. The liked pages also give some rudimentary design

details.

The laminations when assembled from an interleaved ‘stack’ or ‘core’. The

interleaving is usually to avoid any gaps in the magnetic circuit as air is much less permeable

to magnetic flux than iron and steel.

The magnetic flux runs around the two side limbs and combines in the centre limb

which is twice the area of a single side limb, thus keeping flux density constant. The flux

lines that are indicated in red in the diagram at right would follow a slightly higher path near

the corner fixing holes, than my graphic skills can reproduce. It should be noticed that there is

practically zero flux in the centre of the long side and fixing holes or notches are common at

this point.

The ‘holes’ in the core are known as ‘windows’ or ‘window spaces’ and in an

assembled component they are filled by coils wound on a bobbin. Coil formers or bobbins are

of two types known as ‘plain’ or ‘split’, the one shown at left is plain and the other at right is

the split version.

Bobbins these days are mainly injection moulded in plastic, but larger ones often

have paxolin or balkanised paper board cheeks. Occasionally, transformers are constructed

with two or more independent bobbins, each having its own winding(s). this method of

construction is rare, but has it’s uses at very high voltages( above 3,000 volts). The windings

or coils that are wound around these bobbins can be either single coils or multiple ones.

Single coils are a type known as ‘Auto Transformers’ and we will not deal any further with

them as they are generally not applicable to the type of project that I get involved in.

Multiple coil types are known as ‘double wound’ and the windings fall into two

subdivisions… ‘Primary’ and ‘Secondary’ generally there is only one primary although it

may be divided into two or more portions. Secondary windings may be of any number. Coils

22

may be wound side by side on split bobbins or may be wound on top of one another with a

suitable insulation between. Generally the primary or input winding is completed first as the

innermost coil then layers of plastic or paper are placed over the completed primary and this

is then used as a base upon which further windings are made.

8.2 WINDING COIL

Two coils are shown, one crimson and one green, they indicate primary and secondary coils.

An alternating current flowing in the primary coil will cause an alternating flux in the core

which in turn couples with the secondary coil inducing an alternating voltage in it. If this

alternating voltage is applied to a load then an alternating current will result. The ratio of

turns between the primary and the secondary is proportionate (minus losses) to the voltages

on primary and secondary. The number of turns per volt is a function of the cross sectional

area of the magnetic circuit, the duty cycle and the allowable temperature rise. Eddy current

losses are constant and the fraction of primary current that is due to this cause is known as the

‘magnetizing current’/ the resistive losses in the windings, due to the current flowing is

generally known as ‘copper loss’ and is proportionate to the percentage of full load that the

device is run at.

8.3 POWER TRANSFORMER

Power transformers raise or lower the voltage as needed to serve the transmission or

distribution circuits.

Figure 8.2 :- Power Transformer

23

8.4 CURRENT TRANSFORMER

What is the purpose of a current transformer? If measures alternating current flowing through

a conductor. Since it is used to measure current, a current transformer is often classified as a

type of instrument transformer. One could measure the voltage drop across a known resistor.

This is okay for low current applications but is often impractical for high current applications.

The resistor consumes a lot of power (lowering efficiency) unless the resistor is very low in

value, in which case there may be very little voltage to measure. The resistor could be

excessively large. The resistor’s heat may affect the resistor value, thereby reducing the

accuracy of the measurement. A current transformer can accurately measure the alternating

current and put out a reasonable voltage, which is proportional to the current, but without as

much heat and size that an appropriate resistor would require. The current transformer can

perform its function with very little insertion loss into the conductor current being measured.

The current transformer also provides voltage isolation between the conductor and the

measuring circuitry. Proper function of a current transformer requires use of a load resistor.

The load resistor is often referred to as a “burden resistor”.

The best core structure for a current transformer in term of electrical performance is a

toroidal coil. Many toroidal current transformers have only one winding.This winding is

usually a “high turns” winding which functions as the secondary winding. In application, the

toroidal current transformer is slipped over an end of a high current wire or buss bar, which

conducts the primary current. Said wire or buss bar constitutes a one turn primary winding.

Split core current transformers are designed so that they can be assembled around a buss bar

without disconnecting the buss bar. “C”-cores and “U” core structure are commonly used for

split-core current transformers because they are relatively easy to take apart and put back

together around the buss bar. Historically, this has not been practical for toroidal coils, but

there are now some flexible toroids, which permits the “split-core” features of installing it

around a buss bar. They have limited application. Some printed circuit board applications will

utilize bobbin wound current transformer with two or more windings. One windings is an

integral part of the circuitry, while the other winding acts the secondary.

24

Chapter-9

BOILERS

A boiler is a closed vessel in which steam is produced from water by combustion of fuel.

Classification of boilers: -

1. Horizontal, vertical and inclined.

2. Fire tube and water tube.

9.1 WASTE HEAT RECOVERY BIOLER

Wagner-biro supplied boilers for anta combined cycle power plant known as waste heat

recovery boilers (WHRB), which are of non fired, dual pressure, forced circulation type. The

boiler has two different water/steam cycles known as high pressure system and low pressure

system. Each system has its own boiler drum and circulating pumps, and is feed by HP & LP

feed water pumps from a common feed water tank. The pressure and temperature of high

pressure super heated steam is 64 bar and 4900C and that of LP 6 bar and2060C.

The HP & LP steam from the three boiler from four common headers HP live steam

line, HP bypass line, LP live steam line and LP bypass line, the bypass line dump steam in

the condenser through the HP and LP bypass system. The HP steam drives the HP steam

turbine through stop valves and control valves. The LP steam after passing through stop

valves and control valves mixes with the HP turbine exhaust and drivers the gas turbine. This

dual system of operating utilizes the waste heat from the gas turbine with maximum

efficiency. From LP turbine steam enters the condenser where it get condensed to water with

the help of cooling water. Condenser is shell and tube, water flow through the tubes and

steam flow out side. The condensate get collected in hot well, from hot well it enters the feed

water tank through condensate extraction pump (3*50%).

25

Figure 9.1 :- Waste Heat Recovery Boiler

9.2 VARIOUS ACCESSORIES USED IN (WHRB) ARE

1. Super heater

Super heater is used to raise the temperature of steam above the saturation temperature by

absorbing the heat from flue gases which are coming from the diffuser.

Superheated steam has the following advantages: -

Steam consumption of the turbine is reduced. Erosion of turbine blade is eliminated.

Efficiency of steam plant is increased.

2. Evaporator

An evaporator is the component of a refrigeration system and is used to extract heat from the

chamber is to be kept at low temperature. The refrigerating liquid enters the evaporator,

26

absorbs latent heat from the chamber at constant pressure and comes out as a .

3. Economizer

The function of an economizer in a steam generating unit is to absorb heat from the flue gases

and add this as sensible heat to the feed water before the water enters the evaporative circuit

to the boiler .Advantages of economizer

The temperature between various parts of boiler is reduced which result in reduction of

stresses due to unequal expansion .Evaporative capacity of the boiler is increased. Overall

efficiency of the plant is increased.

4. Air Pre heater

An air pre heater is used to recover heat from flue gases. It is installed between the chimney

and economic.

5. De aerator

It is used to remove air from water as air carries oxygen which is corrosive in nature so to

protect the various parts of boiler from corrosion. We add the hydrazine (NH2=NH2) in to the

water which react with O2 and makes the pure water.

6. De super heater

It is used keep the temp. Of super heated steam constant. By spraying of some amount of

water over the superheated steam, we can decrease the temp. of steam to keep it at constant

temp. About 5250 C.

9.3 WHRB-SPECIFICATIN

1. Registration No : RJ-661-RJ 666

2. Constructor’s Name and Address : Wagner-Biro AG

a. Graz-Vienna, Austria

3. Manufactured For : National Thermal Power

a. Corporation (NTPC)

27

4. Contract No. : 01/CC/9505-001-01-1505

5. Type of Boiler : Forced Circulation

Overall Dimension of flue gas path

Width: 6, 4 m

Length: 18, 5 m

Height: 28,0 m

DESIGN DATA: HP-Part LP-Part Cond. Rec.

Design Pressure: 83 bar (g) 9 bar (g) 15 bar (g)

Intended working Pressure: 73 bar (g) 5, 5 bar (g) 11 bar (g)

Shop numbers of boiler: B1 B2 B3 B1 B2 B3 B1 B2 B3

2993 2994 2995 2990 2991 2992 2997 2998 2999

Total heating surface:

Water tubes: 59910m2 23859m2 6715m2

Super heater Tubes 8990 m2 584 m2 -

Steam and condensate 162, 6 t/h 39, 1 t/h 56 t/h

Mass flow:

Final temp. Of steam 488/5010C 2070C 1600C

Firing : Unfired –waste Heat temperature maz 5270 C

Year of Manufacture : 1988

Brief description of boiler : Waste heat recovery boiler with separate High and Low

28

9.4 DE MINERALISED WATER PLANT

In this section D.M. water is prepared for the purpose of steam generation. From the pre

treatment plant sump the water is transported to D.M. plant. The process of manufacturing is

dm water start form activated. The function of a cf. is to maintain level of the chlorine &

turbidity of water. The level of turbidity at inlet of the tank should be less than 2 ntu is naptha

lomateric Turbidity unit & turbidity at the outlet of the tank should be reduced to 0.5 nyu and

the level of the chlorine in the tank is 0.2 parts per million. After this water goes to weak acid

cation. This chamber is used to remove the temporary hardness of the water. The temporary

hardness present in the water is calcium carbonate & bicarbonates compounds. A special

resin is used for this purpose in the chamber. The resin used is 236-H. now water goes to the

STstrong acid cation. Function of this chamber is permanent hardness present in the water.

The permanent hardness compound present in the water is calcium, sodium & magnesium.

The resin used in this cylinder is H-220. After this an action is performed on the water to

remove the carbondi-oxide present in it & this is done by degrer. After the removal of CO2

from the water if goes to weak bare anion. This chamber removes weak anions present in the

water. Some of the weak anions present in water are silica, chlorates, nitrates & sulphates.

The main resin used is this cylinder is ira 90. When the weak anions are removed then the

strong base present in the water removed & this is done through strong base anion. Some of

the strong base present in the water are silica, chlorates & nitrates. The resin used in the

cylinder isffip. Now the water of strong base anion & strong acid caution are mixed & sent to

another cylinder called MImixed bed test This tank completely removes the ions present in

water. From here the ph of water is maintained so that it is neither more acidic nor more basic

& now water is stored in large tanks known as DM.

9.5 PRETREATMENT PLANT

Pre treatment plant is used to supply water for cooling of the various parts of the boiler &

condenser & for manufacturing of Mineralized water. D.M. water is used here because it is

pure and does not corrode the parts of the various components of boiler and condenser. The

process for pre treatment plant is as follows:

First of all the water from Right main canal is taken in to two reservoirs and from

these reservoirs the water is taken into the water house. Three pumps are used for pumping

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this water into aerator. The function of aerator is to add oxygen to the water and to remove

dust particles from the water. From this; water goes to small reservoir, in which chlorination

is done to remove the algae, bacteria and other micro organisms present in the water. After

this the water goes to fore bay storage tank and from here, it goes to pump house where six

pumps are used. Three pumps are used to supply water to De-mineralized water & other three

are used to supply water to Effluent treatment plant. When the water reaches to the pre

treatment plant it is again passed from the aerator, to add oxygen to it. Now water rushes to

stilling chamber where chlorination is done to water for cleaning other micro organisms. The

flow of water at this point can be known by orifice flow meter. Now water is sent to two

clarifiers, from which anyone can be used at a time. In the clarifiers polymer & alum is added

in the centre of the tank purpose of addition of the alum is that it increase the size of small

impurities that are present in the water, but can’t be seen with help of our naked eye & the

function of the polymer is to bond that particles. Now the impurities can be easily removed.

The clarifier consists of three parts is inner most tank in which first water goes. The sludge

settles down & in taken to the sludge put & the clear water is taken to the gravity sand filters.

G.S.F. consists of four layers. First layer consists of large gravel. Second layer consists of

medium size gravel. On the top of that is small size gravel & at top most is present the layer

of sand. From these G.S.F’s the water gets more purified and it goes to D.M. plant.

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CONCLUSION

I have studied about the power plant, especially in ANTA. Studied about gas power plant,

especially natural gas could be used for power generation in gas power plant. It is very

economical but less efficient. Mainly methane (CH4) is used as fuel. It is very profitable in

case of pollution. It is very less polluted. At place of fuel naphtha is used in alternate form.

But it is very costly and polluted. So it is used in very few shortages. This is very profitable

plant because it has combined cycle plant. According to combined cycle plant less

temperature gas will be recycled and used for generation of power. ANTA gas power plant

has four units in which three gas units and one steam unit. ANTA gas power plant has more

plants for reduction for pollution approximately 1.8 lac trees.

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BIBLIOGRAPHY

1. “A Text Book Power Plant Engineering”,R.K. Rajput, 4th Edition.

2. “Power Plant Engineering”, A.K. Raja, 1st Edition.

3. “Steam &Gas Turbine and Power Plant Engineering” , Dr. R.Yadav ,7th Edition.

4. “NTPC reference guide”

5. “Notes given during training period”

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