ABSTRACT

According to the rules of Rajasthan Technical University, I have undergone my 30

days Practical In plant Training at NTPC, Anta which is incorporated in the

syllabus for 4 year B.Tech. Course. The training report hereby submitted outlines

the course of work during my training in an oriented manner over a period of 30

days for Electronic Instrumentation and Control branch.

The whole capacity of plant is 419.33 MW with 4 generating units. The

report consists of generation of electricity in its 4 units & constructional features

of main parts of plant. Adequate diagrams and layouts have been provided for a

more descriptive outlook and clarity of understanding.

In all, I have tried my best to present this report in a very precise and

profitable manner. Engineering students gain theoretical knowledge only

through books, which in not sufficient for absolute mastery in our field.

Thus, I made a sincere attempt to bring about the details which I

experienced during my training at “NATIONAL THERMAL POWER CORPORATION

(ANTA)” from 15 JUNE TO 14 JULY 2011 through this report. I have tried my best

to reproduce the facts & findings of the training site.

1

CHAPTER -1

INTRODUCTION

1. BRIEF NTPC-AN INTEGRATED POWER MAJOR

A journey towards excellence established in 7 Nov. 1975, NTPC limited, a

premier sector enterprise, is India’s largest power utility with an installed capacity

of 27,904MW through 26 power station including station operated under joint

exploration, power distribution trading and also plans to enter into nuclear power

development. NTPC plans to become a 50,000MW Company by 2012 and

75,000MW plus company by 2017. The company contributed 29.25% share of

the total installed capacity of the nation including capacity and generation of joint

venture companies

.

Figure 1.1

2

1.1 COMBINED CYCLE TECHNOLOGY:-

The year was 1985, government of India decided to effectively use the

“sweetened natural gas”, which was to be made available by “GAIL” through

cross-country HBJ gas pipe line NTPC was entrusted with a responsibility to set

up gas based power project in Gujarat, Rajasthan and Utter Pradesh, NTPC

submitted the feasibility reports for 3 gas based projects at Anta (Rajasthan),

Auraiya (U.P) and Kawas (Gujarat).

The feasibility report of anta was approved by government of India in

October, 1986. The land was simultaneously acquired, bhoomi poojan of the land

to start the work performed on 16.01.1987 by the then CMD shri M.L. shishoo,

and the charging of “construction power” was inaugurated.

3

1.2 MILE STONE:-

Govt. approval of feasibility report - 20.10.86

Bhoomi poojan - 16.01.87

Award of main plant turnkey contract - 24.08.87

Synchronization of GT-1 - 20.01.89

Synchronization of GT-2 - 04.03.89

Synchronization of GT-3 - 04.05.89

Synchronization of ST - 09.03.90

Location : anta in Baran district of Rajasthan

Total land : 390.75 acres.

Fuel : natural gas naphtha

Water source : KOTA RIGHT MAIN CANAL

Net plant output : 419.33 MW

4

1.3 SALIENT FEATURES OF ANTA

1. GAS TURBIN :89, TYPE 13D-2, ABB MAKE, 5TH

STAGE REACTION TURBINE

2. GT COMPRESSR : 18TH ST; AGE AXU\IAL FLOW,

REACTION BLADING

3. COMBUSTION CHAMBER :SINGLE SILO TYPE, DUAL FUEL

FIRE BURNER

4. AIR INTAKE FILTER :SELF CLEANIN, SYNTHETIC PAPER,

TOTAL 945 FILTERS IN THREE TIRES

5. BYPASS STACK :VERTICAL 25M. HIGH

6. WASTE HEAT RECOVERY :DUAL PRESSURE, DOUBLEDRUM,

UNFIRED, FORCED CIRCULLATION

BOILER PRESSURE FLOW TEMP

HP 62.70 BAR 163 T/HR 485℃

LP 5.5 BAR 39.1 T/HR 207℃

7. STEAM TURBINE :153.20MW, TANDEM COMPOUNDED ,

DOUBLE EXHAUTST, CONDENSING

TYPE, SINGLE FLOW HORIZONTAL

25 STAGE HP TURBINES.

8. CONDENSOR :DOUBLE PASS SURFACE

CONDENSOR WITH STAINLESS

STEEL TUBES, COOLING 13988M3.

5

9. GENERATOR :3 PHASE, TWO POLE, IR COOLED

OUTPUT VOLTAGE SPEED

GTG.135MVA 10.5KV 3000RPM

STG. 191MVA 15.75KV 3000RPM

10.BLACK START FACILITY : 2.4MW DIESEL GENERATOR SET, V-

6.6KV

11.COOLING SYSTEM FOR :3*50% COOLING WATER PP AND

CONDENSER 2*50%COOLING TOWER

PP, CAPACITY 15000M3 EACH, 11 NOS

ARIFLOCCUATORS, CAP. 110M3/HR

12.PT. PLANT :2 NOS AIRSLOCCULATORES,

CAP.110M3/HR

13.DM. WATER PLANT :TWO STEAM OF 35M3/HR EACH

14.NET PLANT OUT :419.33MW

15.FUEL :NATURAL GAS (MAIN FUEL),

THROUGH HBJ PIPE LINE, NAPTHA,

(ALTERNATER) FUEL BY ROAD

TANKER

16.WATER SOURCE :KOTA RIGHT MAIN CANAL

17.RESERVIOUR :10 MILLION M3, FOR 1 MONTH

18.TOTAL LAND :390.75 ACRES

19.PLANT OUTPUT :419.33MW

6

CHAPTER -2

GERNAL DESCRIPTION OF COMBINED CYCLE

The 419.33MW anta combined cycle power plant consist of three gas turbines

generator sets of 89.20MW each and one steam turbine generator set of 153.20

MW. The gas turbines are equipped with a dual fuel burner for gaseous fuel

(natural) and liquid fuel (naphtha). The station can be operated in the open cycle

mode via their exhaust gas bypass stacks or as modules together with their waste

heat recovery boilers and STG in the combined cycle mode.

The WHRB’S is designed as dual pressure boilers with high pressure (HP)

and low pressure (LP) sections and condensate preheating at the tail end. The

condensate pumped from the condenser hot well is degasified in the deairator at

constant pressure and stored in the feed water tank. From feed water tank, the

boiler feed water is extracted by mean of separate boiler feed water pumps for the

HP and LP system serving the 3 WHRB’S in common HP and LP main steam

lines the turbojet is composed of single flow HP turbine and one double flow LP

turbine. The generator is directly coupled to the shaft of LP cylinder. The exhaust

steam of the STG is condensed in a surface condenser cooled by fresh water of

the right main Kota canal in the once through cycle. During the shutdown of

canal, the condenser is cooled via a wet cooling tower in the closed cycle

alternatively.

For start-up and shutdown as well as trip of STG one common HP and LP

steam bypass station for all 3 modules are provided leading the steam directly into

the condenser.

7

1. PRINCIPAL OF COMBINED CYCLE:-

The function of a gas turbine in a combined cycle power plant is to drive a generator, which produces electricity, and to provide input heat for the steam cycle. Power for driving the compressor is also drive from gas turbine.

Combined cycle power plant integrated two power conversion cycles namely, Brayton cycle (gas turbine) and rankine cycle (conventional steam power plant) with the principle objective of increasing overall plant efficiency.

Figure 2.1 Figure 2.2

2. BRAYTON CYCLE

The Brayton cycle, named after the American engineer George Brayton (that built a two-stroke reciprocating engine in 1876 and advanced combustion chambers at constant pressure ), is a good model for this operation of a gas-turbine engine

8

(first successfully tested by F.Whittle in 1937, and first applied by the Heinkel Aircraft Company in 1939) ,nowadays used by practically all aircraft except smallest ones, by many fast boats and increasingly been used for stationary power generation, particularly when both power and heat are of interest.

In the ideal air-standard Brayton cycle, the working fluid is just air, which is assumed to Follow four processes is entropic compression, constant-pressure heat input from the hot source, isentropic expansion, and constant pressure heat rejection to the environment. Contrary to reciprocating engines, the gas turbine is a rotating device working at a nominal steady state (it can hardly work at partial loads) spark ignition is used to start up, since air compressor output temperature is not high enough to inflame the fuel.

THEIDEAL BRAYTON CYCLE IN THE T-S AND P-V DIAGRAM, AND THE REGENERATIVE BRAYTON CYCLE

Figure 2.3

3. RANKINE CYCLE:

The conversion heat energy to mechanical (or electrical) energy with the energy of steam is carried out by this cycle. In its simplest form the cycle works as follows. The initial state of working fluid is water which, at the certain temperature is compressed by a pump and feed to the boiler. In the boiler the compressed water is heated at a constant pressure. Modern steam power plants have steam temperature in the range of 500-5500C at the inlet of turbine.

9

Figure 2.4

4. ADVANTAGE OF COMBINED CYCLE PLANTS:

In addition to higher energy efficiencies, the advantages of combine-cycle units over more conventional power generation sources include the following advantages:-

1. Lower construction and maintenance costs2. Low gestation period3. Better reliability

10

CHAPTER -3

GAS TURBINE

GENERAL DESCRIPTION-

A gas turbine plant in its most simple form consist of the following main part

1. Air intake system

2. Compressor

3. Combustion chamber

4. Turbine

5. Generator

1. AIR INTAKE SYSTEM:-

The air flow radial inward through the filter elements then upward to clean air

duct. The air inlet connection has horizontal air inlet and situated axially in front

of the compressor. three are three horizontal floors in t filter house each floor

carry 315 filters. (Total filters are made of synthetic and cellulose fibers, using

resign impregnated).

11

2. COMPRESSOR:-

It is 18 stages with additional inlet guide blade, axial flow, reaction compressor.

The blade of the 18 rotor and 19 fixed rows are made of high tensile ferric

chrome steel.

The compressor casing is horizontally split at axis, and is made of spherical

graphite cast iron. This material possesses high tensile strength and good

expansion quality. upper and lower halves of the compressor casing are provided

with robust flanges and are held together by expansion studs with socket head.

The compressor casing has three circular ducts at 4 th, 7th, 10th row of fixed

blades. These ducts are closed to the outside by four bleed halves. Bleed halves

are kept open unto 2700rpm,so that certain amount of compressor air can be blow

off. These bleed valves reduces the external power input required running

compressor during start up.

3. COMBUSTION CHAMBER:-

In combustion chamber, the air compressed and supplied by compressor is

brought to the required process temp. by combustion of liquid/gas fuel. The single

combustion chamber is fitted with only one duel fired burner and mounted

vertically on the compressor/turbine assembly.

The combustion chamber is all welded steel plate fabricated. The main

parts are jacket with cover, lower upper combustion chamber bodies, finned

segment body, burner and inner casing.

12

Combustion chamber jacket, which houses the components, is made of heat

resistant, low alloy ferrite steel. Finned segment body encloses the hottest zon e

of the combustion chamber.

The air from the compressor enter the combustion chamber from below and

flow upward through the annular space between combustion chamber jacket and

inner section of the lower combustion chamber body. Approximately 30% air

flow enter the combustion chamber through eight mixing nozzles provided at the

lower body as secondary and approximately 30% air flow enter the combustion

chamber through upper body via fined segment row (there are 5row, the

remaining 40%flow as primary air for combustion, into the swirl insert and enter

the combustion space with turbulence. After the fuel has ignited these gases are

thoroughly mixed with secondary air form mixing nozzles and brought to the

permissible turbine inlet temp.

The inner casing guides the hot gases coming from combustion chamber to

the turbine halding.it is thin welled construction made of heat resistant chrome-

nickel austenitic alloy.

4. TURBINE:-

Turbine is five stage reaction turbines. Due to high temp. of incoming gases, the

first and second row of rotor and fixed blading are air cooled with air from

compressor discharge. The cooling air is fed to the first and second row of fixed

blades through holes drilled in the blade carrier and to the first & second row of

rotor blades through hole drilled in shaft. Cooling air passes along several holes

13

made in blades and finally blowing out through numbers of slits in the

trailing/leading edge of the blade. This method of cooling ensures that blades are

thoroughly cooled, thereby avoiding cracks induced by thermal stresses. These

cooled blades are fixed rotor blades of other rows are made of cast in nickel based

alloy. The fourth and fifth row of rotor blades fifth row of fixed blades are drop

forged. turbine outer casing is split into two halves like compressor casing are

bolted together at radial flange with expansion bolts, turbine casing is made of

heat resisting ferrite steel in order to with stand thermal stresses. The blade carrier

for turbine fixed blades is made of ferrite steel alloy casting and axially like

turbine/compressor.

Figure 3.1

4.1 FEATURES OF ABB 13D2 TYPE GAS TURBINE-

1. A single shaft of welded construction.

2. Axial compressor of 18 stages with bleed valves after 3 rd,6th ,9th stages for

protection against surging and also reduced power required for startup.

14

3. A single combustion chamber with a single burner. The combustion chamber is

mounted vertically on the turbine outer casing. The large size of the combustion

chamber provides easy access to inspection of its internals as well as approach to

the turbine inner casing and first stage blades of turbine.

4. The burner is of dual fuel design and either gas, naphtha (or any liquid fuel) or

both can be fixed.

5. Five stage axial turbine with axial exhaust for easy connection to a waste heat

boiler. First two stages of turbine blades are coated.

6. First five stages of compressor blades are coated to protect against corrosion

due to humidity.

7. First 2 stages of turbine blades are coated against high temperature corrosion.

4.2 OTHER CHARACTERISTICS OF GAS TURBINE-

1. The gas flow ducts must offer minimum hydraulic resistance.

2. The axial flow at exit from last stage of a gas turbine constitutes 150-200 mm/s

and the kinetic energy of the gases attain 10%of the total useful energy. To

minimize losses an exhaust diffuser is provided.

3. If the ratio of mid diameter of stage to blade height is less than or equal to 12 to

14 twisted blades are decided.

4. There is no extraction like in steam turbines hence the flow path is simpler.

15

5. Liquid fuel usually contains impurities like VA, NA, S, etc. These substances

destroy corrosion protective film on heat resistant steels.

6. Along with use of high temp and heat resistant metals, various design

techniques are employed to reduce temperature levels and remove heat from the

hottest elements in gas turbines. As much as 15% of compressor discharge air is

used for cooling of blades, rotors and blade carrier etc.

7. First rows of blades are made hollow or have longitudinal bore holes for

cooling. Non solid and often have a thinned portion at the tip to minimize risk of

damage on contact with the turbine casing.

8. Gas turbine rotors are usually disc type with intense cooling arrangement.

9. Turbine blade carrier is horizontal split and is of strong and stiff designs in

order minimize radial blade clearances. Hence casing is made of symmetrical

cross section and with uniform wall thickness in order that temperature

deformations due to frequent and sharp changes in turbine operation could not

distort the cylindrical shape from inside. To lower casing wall temperature heat

shields and cooling is provided.

10. there is no governing stage in gas turbine. Partial admission is not permissible

and load control is only control through of TIT.

4.3 GAS TURBINE PLANT OPERATION:-

The compressor sucks in air from the atmosphere through the filters called air

intake filters. The compresses air at approx. 9 to 11 bar passes into the

16

combustion chamber where it is used as primary air for combustion and

secondary air for cooling of very hot parts.

The gas turbine generates the necessary power to drive the axial-flow

compressor and the generator. The turbine and compressor are in common casing.

Start-up of the GT is drives with the help of starting equipment which runs

the generator as a motor with speed increasing from 0 to 600 rpm. At this speed a

pilot is ignited in the combustion chamber, fuel (gas/naphtha) enters and

combustion takes place.

The speed increases further both with the help of generator motoring and

the combustion of fuel up to about 2000 rpm. At this speed starting equipment is

switched off and only the generator is made ready for synchronization with the

grid. After synchronizations, the turbine load increases up to the base load with

more and more fuel entering the combustion chamber.

The hot gases after combustion enter the gas turbine at about 1000℃ (at

base load). The higher pressure and temperature gas pass through the turbine

rotating it and generator, this produces the electrical power.

The exhaust gas coming out of the GT is at about 500℃. This can be

utilized to produce steam in WHRB.

17

Figure 3.2

4.4 ADVANTAGES OF GAS TURBINE OVER STEAM TURBINE

1. Gas turbine is more compact. There is no boiler or condenser. Auxiliaries are

very few.

2. They can be started and loaded very quickly(within 20 minutes form cold start

to full load)

3. Gas turbines are simpler in maintenance and designs.

4. Gas turbine plants involve less metal and material.

5. They are lower in cost for installation capacity.

6. Gas turbines don’t require enormous quantities of cooling water as in steam

turbines.

18

4.5 DISADVANTAGE

1. Gas turbines have lower specific power.

2. They have lower efficiency.

3. Gas turbines have shorter service life.

4. They are very sensitive to fuel quality.

5.GENERATOR

Generator is three phases, two pole air cooled machine. The generator and turbine

are placed on common and plane concrete foundation, with same centre line level

for turbine and generator rotor.

The mechanical energy generated by turbine is converted to electrical

energy by the generator and appear in the stator winding in the form of current

and voltage. That balances the torque of the gas turbine.

It leads the magnetic flux, and carries the field winding, the generator id

self excited. The power required for the excitation is % taken from the generator

term finals and fed to the field winding through the excitation transformer and the

thruster- controlled rectifier units.

19

5.1 GAS TURBINE GENERATOR (Mka):-

1. Generator Type : wy18 L-095ll

2. No. of phases : 3

3. No. of poles : 2

4. Stator winding : star

5. Insulation class : f

6. Nominal apparent power : 135MVA

7. Nominal voltage : 10.5kv

8. Nominal current : 7423a

9. Reactance

A. Direct axis synchronous reactance ad : 191%

B. Direct axis transient reactance x’d : 14.4%

C. Direct axis sub transient reactance : 10.2%

D. Negative sequence reactance x2 : 12.8%

E. Zero sequence reactance x0 : 5.8%

F. Short circuit ratio kc : 0.58%

10.Full load efficiency : 98.38%

11.Stator winding resistance at 200c : 0.000607 ohm

12.Rotor winding resistance at 200c : 0.2177 ohm

13.Stator winding capacitance ph. to core : 0.52 micro F

14.Weight, generator assembled : 162 MT

15.Rotor weight : 31 MT

20

CHAPTER -4

FUEL SYSTEM

1. GAS:-

Gas comes from GPRS bars at around 18 bars; manual isolation valve is to be

opened by operator. Motorized stop relief valve is depressurized. When valve

opens, the relief port is closed.

In the gas control block there is an emergency stop valve(ESV). This opens

with the help of power oil pressure against spring force. Whenever, turbine trip

the oil is drained (depressurized) and spray force closes the valve cutting off gas

supply to combustion chamber.

2. NAPHTHA:-

Naphtha comes from naphtha solution via the forwarding pumps at around 15bar.

Manual isolation valve outside GT hall is to be opened by the operator manual

isolation valves before main fuel pump and also to be opened. Motorized valve

will be opened by GT program and when FG liquid fuel is selected. NAPHTHA

then passes through duplex filter to the main fuel oil pump, which raises the press

to approx. 80 bar. There is release valve which opens when firing speed is

reached (600 rpm)

21

There is an emergency stop valve similar to one in the gas scheme. Finally

there is the control valve directly coupled with the NAPHTHA nozzle. A

minimum opening of the nozzle is already pre-set. once stable flames formed, the

nozzle opening increases with the control valve opening.

3. LUBRICATING OIL/POWER:-

The turbo generator set has four bearing which are continuously supplied with

lubricating oil form MOT which is located between the compressor and

generator. There are two bearings on either side of generator and one bearing at

turbine end bearing at compressor end.

AN auxiliary lube pump (AC motor drive) supplies lube oil during the start

up and during rotor turning operation in case of AC supply failure DC lube oil

pump will start automatically. there are two high pressure AC motor driven

jacking oil pumps there function is lift the turbine/generator slightly, during start

up, so that starting force is reduced.

A vent fan mounted on the MOT keeps it under vacuum and removes the

fumes/vapours to atmosphere.

Barring gear pump-AC motor driven pump rotates the shaft in term intently

during rotor-turning operation to prevent sagging of rotor .in case of an auxiliary

power oil pump (AC pump) driven provides hydraulic oil for operation of

hydraulically operated valves. A motor driven circulation pump keeps oil in

circulation through power oil system when the GT is under shut-down, to avoid

ingress of air.

22

During normal operation all the above pumps remain off. the lube and

power oil are provided by a shaft driven main oil pumps located inside the Gear

box on the top of the MOT.

Lube oil is cooled in coolers outside GT hall. These are air cooled radiator

type coolers. Lube oil passes through tubes and air passes over these tubes

induced by 3 fans.

After cooler, the oil is passed through duplex type filters and goes to

bearings.

23

CHAPTER -5

BOILER

The boiler installed in national thermal power corporation is manufactured by “Austrya”. The boiler is used to generate high pressure, super heater steam which is ultimately used to drive the turbine coupled to the generator hence producing electrical power.

Boiler unit comprise to following units:-

1. Boiler2. Super heater3. Economizer

The steam generator is of radiant reheat, natural, circulation, single drum, dry bottom an semi out door type unit, designed for firing gas as principle fule.

The super heater steam has mainly three sections. The low temperature super heater, the radiant temperature super heater (arranged at the out section of furnace) and the final super heater (arranged after re-heater).

Two super heater, de-heater are provided in between the list section and platen super heater for controlling super heater steam temperature over wide load range. The complete back pass of the boiler (up to economizer) has been covered with steam cooled super heater wall section the complete re-heater has been arranged as one section and located in the horizontal pass of the boiler in between the radiant platen super heater and final super heater. Two re-heater de-super heater are provided in the cooled re-heated inlet, hot re-heater outlet, economizer inlet heaters are provided with required guides to take care of forces and moments from external, piping connections.

The complete part system is suspended from the boiler structure steel roof section and arranged for expansion downward.

24

1. SYSTEM DESCRIPTION OF WHRB:-

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 are feed by HP&LP feed water pumps from a

common feed water tank. The pressure and temperature the HP&LP steam from

the three boilers from four common headers HP live steam line, HP bypass line,

LP live steam line, LP bypass line, the bypass line dump steam in 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 drives the gas turbine. This dual system of operating

utilizes the waste heavy 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 outside. The condensate get collected in hot well, from hot well it

enters the feed water tank through condensate extraction pump (3*50%) via the

help of (2*50%) vacuum pump.

Each of WHRB is feed with waste heat flue gas from the respective gas

turbine (GT). The gas turbines are fired either with gas or naphtha. The flu gas

temperature at boiler inlet is about 500c depending on GT load and outside

25

temperature conditions. The flue gas temperature at boiler outlet is about 110c-

140c to avoid cold end corrosion.

During WHRB operation the flue gas is led through a horizontal duct with

integrated silencer to diverter flap of the WHRB. There two positions of diverter

flap, one open to the boiler and another is open to bypass stack.

The energy from waste heat flue gas is transferred to water/steam by means

of heating surface of super heaters, evaporators, economizers and condensate

preheater.

The heating surface of each boiler is about 96000sq.m. The heating

surfaces in staggered arrangement are manufactured as finned tubes arranged

horizontally and installed in vertical duct supported by tube plates.

The steam water system consist of a high (HP) and low (LP) pressure

system and in addition there is a condenser preheated in order to obtain a higher

efficiency.

26

Figure 5.1

27

Figure 5.2

2. COMPONENTS OF WHRB

2.1 LP-BOILER PART:-

2.1.1 ECONOMIZER:-

The LP feed water, which flows from the (3*50%) LP feed water pumps through

the common feed water line to the 3 WHRBs in parallel, enters a WHRB at

economizer gate valve. The gate valve is equipped with a parallel bypass valve,

which is used for first filling of WHRB and pressure equalization.

In economizer the feed water is heated up by the flue gas. After the

economizer the feed water enters the LP boiler drum through feed regulating

28

station (FRS), where the feed water control valve ensures the correct supply of

feed water to the boiler.

Another part of feed water after economizer is branched to the feed water

tank, where it used for de-airating purposes.

2.1.2 LP-BOILER DRUM-EVAPORATOR:-

The feed water in LP boiler drum is pumped through evaporator by means of

(2*100%) LP circulation pumps. In evaporator the water is partially by the flue

gas passing at the outside of the evaporator tubes. The steam and water mixture

again enters the drum, where steam is separated and this steam flows to the LP

super heaters and water is circulated again. Low level and high level protections

are provided for the protection of one vent valve is mounted on the drum which

opens automatically during start and closes when the pressure in drum rises above

1bar.2 nos. of safety valve with silencers are also mounted against the over

pressure protection. The circulation pumps ensure the correct water flow through

the evaporator for which the differential pressure between discharge and suction

side of pump is supervised by means of pressure differential switch. When the

pressure drops the stand by pump will starts immediately.

2.1.3 LP- SUPER HEATER:-

The steam leaving at the top of the LP drum flows through the flue gas heated

Super Heater, where it reaches the end temperature of about 206c.

29

The outlet header is equipped with motorised drain valve which is

automatically operated during start-up and this valve closes automatically after

pressurization. At outlet pipe a safety valve protects the super heater against over

pressure.

2.2 HP-BOILER PART:-

The principal design of the HP-boiler part is the same as for the LP-part.The basic

difference is of operating pressure.

2.2.1 ECONOMIZER:-

The HP fed water, which flows from the (3*50%) HP feed water pumps through

the common feed water line to the HP part of 3 WHRB in parallel, enters a

WHRB at the gate valve of economizer. This gate valve is equipped with a

parallel bypass valve as in LP-economizer. The HP economizer coils are in two

parts, one part is just below the LP economizer and the other is below the LP

super heater and both the coils are connected in series. After the economizer the

feed water enters the HP boiler drum through high pressure feed regulating

station (FRS) , where the feed water control valve ensures the correct supply of

feed water to the boiler..

The HP/LP economizers are provided with safety valves against the

protection of over pressure.

30

2.2.2 HP- BOILER DRUM, EVAPORATOR:-

The feed water in the HP- boiler drum is pumped through the evaporator by

means of 2x100% HP circulation pumps in the evaporator water is partially

steamed as in LP part, this partially steamed water enters in HP drum where

steam is separated, and water is circulated again. These steam is super heated in

HP super heater.

The HP circulation pumps ensure the correct water flow through evaporator

for which differential pressure switches are provided.

One vent valve and two nos. of safety valves with silencers are also

mounted on the HP drum just like the LP drum.

2.2.3 HP-SUPER HEATER:-

The HP super heater consists of two parts with a spray attemperator between

them. This configuration allows the temp. control of the super-heated steam. the

spray water which is cooling medium is branched from the feed water line at the

HP economizer inlet via a control valve to the attemperator if the temp. of super-

heater increases beyond the predetermined temp.

Then spray water control valves opens automatically and keeps down the

super heater tank at about 4980c. The outlet is equipped with mortised drain

valves. A safety valve is also given against the over protection.

31

2.3 CONDENSATE PREHEATER:-

The main condensate is pumped by 3x50% condensate extraction pumps (CEP) to

the feed water tank. Before entering the feed water tank the condensate is passed

through the condensate preheaters which are situated at the tail end of the WHRB

and heated by the flue gas to achieve the highest cycle efficiency.

By means of the 3-way control valve the preheaters can be partially or

totally bypassed.

At certain load conditions and also depending on ambient temperatures, it

is necessary to increase the condensate temperature before entering the preheater.

This is to avoid drop of the flue gas temperature below the sulphuric dew point,

which would cause corrosion at the preheaters. For this purpose 2x100%

condensate circulation pumps are installed. These pumps take automatic start

when the condensate temperature falls below a certain limit.

2.4 BLOW DOWN TANK:-

One blow down tank is provided for each WHRB to collect drains e.g. CBD, IBD

and drum over flow water from HP and LP system of WHRB. The water level in

this tank is maintained through an over flow pipe, which leads the water to hot

drain collecting system. The steam flows via a silencer to the atmosphere.

32

CHAPTER -6

STEAM TURBINE

GENERAL DESCRIPTION:-

The steam turbine consists of two turbine sections, a single flow high pressure

turbine and double flow low pressure turbine arranged in same center line. The

shaft turning gear is engaged and disengaged automatically when turbine is

started and shutdown.

HP live steam is taken from the boiler HP system through the main steam

pipe to the combined main stop and control valves. From there it flow through

four opening in the outer casing into the interior of the HP turbine and enters the

reaction blading through exhaust connection at the top of the HP casing. The

cross over the pipe between HP and LP turbines brings the steam to the reaction

blading in the LP turbine, where it expends down to condense pressure.

The LP steam is taken from LP boiler system through the LP steam main

line to the combined stop and control valves. From there LP steam enters the

cross over piping, where it mixes with the HP exhaust before entering the reaction

blading of the LP turbine. In LP turbine expansion take place and finally steam

get condensed in the condenser.

The turbo generator set has four bearing which are continuously supplied

with lubricating oil from MOT like gas turbine. There are two bearings on either

side of generator and one bearing at HP turbine end one bearing in between HP.

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CHAPTER -7

POWER PLANT CHEMISTRY

Figure 7.1

1. SHORT TERM PLANNING:

Under short term planning work elements are established as follows:

Work receipt and control, i.e. work order system

Planning and scheduling

Preventive maintenance work programs

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Integration of PM schedule with corrective maintenance to minimize

downtime

Condition monitoring

Plant and work history recording

Work management analysis and management reporting

2. CONDITION MONITORING:-

The condition monitoring mainly covers the vibration measurement of rotating

equipment’s, to analyse any abnormality or high vibration, to measure the sound

level and analysis of lubricating oil.

3. LONG TERM PLANNING:-

The major functions of the long term planning are as follows:

Compilation of the station five year rolling plan

To prepare and ensure all necessary arrangements for the following

years overhaul work programs.

Produce, distribute and monitor major overhaul and control

programmed

Custody of all licenses of equipment covered under Indian boiler

regulation act, Indian electricity act, Indian explosive act and other

safety rules and to take action for renewal of these licenses.

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4. STATUARY REQUIREMENT:-

The long term planning engineer is also responsible for the safe custody of all

licenses and takes advance action for the renewal of such licenses. At anta the

following licenses are being taken as the statuary equipment:

a) Factory licenses

b) Licenses for storing naphtha fuel

c) Licenses for storing diesel

d) Licenses for HP boiler drum(3nos)

e) Licenses for LP boiler drum(3nos)

5. PERMIT TO WORK SYSTEM (PTW SYSTEM):-

Permit to work is a written permission to carry out the work on any equipment/

system. This system is required because the electrical and mechanical items of

plant and apparatus are interconnected to from electromechanical systems and

contain inherent dangers. Hence, while working on any equipment/ system, it is to

be ensured that it is safe to work on.

The permit to work system followed at anta is computerized one. The

permit to work is always issued by the operation department and taken by the

respective maintenance department. Each permit to work has unique PTW

number so that identification is easy. The procedure which is followed is issue

any permit to work is follows:

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a. Whenever any work is to be done on any apparatus/ equipment in the plant

area respective maintenance person applies for a permit to work. Permit to

work is must for any work to be done in the plant area which may affect the

normal operation of the plant.

b. After receiving the permit to work request, operation engineer carry out the

isolations as required. The isolation which is required is jointly finalized by

operation and maintenance engineers. Maintenance engineer specifies his

equipment keeping in mind the safely and operation engineer take care of

the process requirement.

c. A danger tag is attached to the electrical supply or at the control station

mentioning the PTW number and name of the equipment etc. After

carrying out the isolation.

d. When it is ensured that the equipment/ system are isolation and safe to

work on, permit to work is issued after signature of the operation and

maintenance engineer.

After issuance of permit to work, the required work is being carried out by the

maintenance department. Every permit to work has duty. Time and date and

permit to work should be returned by in case the work could not be completed till

that time may be extended by operation engineer on the request of maintenance

engineer the procedure for cancellation of permit to work is follows:

a. After completion of work and clearance from the permit to work holder

(maintenance engineer) certifying that “all men and material removed and

equipment is ready to be put in service”, the isolations done are removed

by the operation engineer.

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b. The trial run of the equipment is taken jointly, wherever required. After

satisfactory trial run, the permit to work may be closed.

c. The details of the work done are entered in the computer and permit to

work is closed by operation engineer.

6. POWER EVACUATION:-

There are total 220 kava transmission lines for evacuation of power generated at

anta. There are two lines for Bhilwara, two lines for Jaipur and one line for Kota.

One lines for Rawatbhata power plant

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CHAPTER -8

WATER TREATMENT PLANT

The principle problem in high pressure boiler is to control corrosion and steam

quality. Internal corrosion costs crores of rupees in repair. Without strict control,

impurities in steam also form deposit over turbine blades and nozzles. The

impurities present in water are as follows:-

Un-dissolved and suspended solid materials.

Dissolved slats and minerals.

Dissolved gases.

Other minerals (oil, acid etc.).

Turbidity & Sediment.

Silica.

Micro Biological.

Sodium & Potassium Salt.

Dissolved Sales Minerals.

O2gas.

CO2 gas.

Thus to make water pure for feeding in B.F.P. and to have protection against

corrosion and other above mentioned problems de-mineralisation is needed. The

procedure is explained as-

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1. D.M. PLANT

In this plant process, impure water is fed. This plant consists of two streams,

each stream passes through activated carbon filter, weak acid, cation exchanger

and mixed bed exchanger. The impure water is fed to DM plant through 250 dia.

header from it is taken to softening plant. Two filtered water booster pumps are

provided on filtered water line for meeting the pressure requirement in DM Plant.

Sodium Sulphate solution of required strength is dosed into different filtered

water streams by means of dosing pump to neutralize chlorine prior to activated

carbon filter. Water passes through an activated carbon filter to remove residual

chlorine from water. Water then goes to weak base anion exchanger unit & enters

de-gasified unit where free CO2 is scrubbed out of water by upward counter flow

of low pressure air flow. This de-gasified water is pumped to strong base

exchanger (anion exchanger).

Figure 8.1

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2. C.W. PLANT

Circulating water pump house has pumps for condensing the steam for condenser.

After condensing the water is discharged back into the river. Each of the 5 pumps

for 1st and 2nd unit has capacity of 8275 M3/Hr, and develop pressure about 1.94

kg. /Cm2. 3 seal water pumps are used for sealing circulating water pump shaft at

pr. 4.5 kg./cm2. One pump is taken standby at a time.

From main line water passes through filter bed to filter the water. Clarified

water is pumped to 42 m elevation where water is stored in tank and used for

cooling the oil coolers and returns back to river.

3. B.C.W. PUMP HOUSE

Filtered water after demineralization is used for Bearing Cooling from BCW

pump house. Water enters at 30-32oC and leave exchanger at 38oC. The raw

water used in ash handling plant and remaining quantity is stored in BCW Pump

House. From here the water is pumped to CW pumps. BCW here stand for water

used for cooling oil used for cooling the bearing. In CW pump house water is

discharged from nozzle and impinged for travelling water screens for cleaning it.

41

CHAPTER -9

MAINTENANCE MANAGEMENT

The maintenance management system consist mainly the following areas

Preventive maintenance/ lubrication schedule.

Break-down maintenance.

Capital overhauls/ scheduled inspections.

Condition monitoring.

Spare parts management.

Statuary requirements.

Short term planning engineer.

Long term planning engineer.

Spare parts management and spare parts development.

The short term planning covers the preventive maintenance, lubrication

schedule, break-down maintenance and condition monitoring.

The long term planning covers the capital overhauls, scheduled inspections

and statutory requirements.

The spare parts management and spare part development is the third area

looked separately by one engineer. The anta gas power project being completely

imported plant supplied by M/S ABB, Germany on the turn-key basis, the spare

part indigenization has been given due importance.

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ANGPP has four discipline of the maintenance section as follows:

Mechanical maintenance section

Electrical maintenance section

C&I maintenance section

Civil maintenance section

Each of section is headed either by manager or senior manager (E5/E6) and the

area engineers are as follows:

Mechanical maintenance section 5nos.

Electrical maintenance section 4nos.

C&I maintenance sections 6nos.

Civil maintenance section 2nos.

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CHAPTER -10

CONCLUSION

Electricity has a prominent role to play in life. It is a vital to all segments of the

economy. It is a precursor to the progress and prosperity of the nation.

Government of India has a target of per capita availability of electricity to be

increased to over 1000 units and minimum lifeline consumption of 1unit/house

hold/day as a merit good by year 2012. In electricity the more you supply the

greater is demand as supply of power causes economic development and

increased standard living which enhances the demand. The digital economy

enterprises data warehouses, call centres, software technology parks and other

computer control mission critical businesses are the fastest growing segments of

power consumers.

These enterprises require nearly 100% up time to guarantee integrity of

their products and services. The power sector has made rapid strides in absolute

term on. III the spheres viz. generation, transmission network and energy mix.

Despite these achievements the power sector has been plagued by serious

shortages of electricity, as it has not been able to keep pace with rapid growth in

demand. However the power sector has reached a point, from where it is possible

to consolidate the growth made till now and sustain and enhance that growth to

keep pace with economic development.

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SCHEDULE OF THE INDUSTRIAL TRAINING

DURATION- 30 days(15 June – 14 July)

DATE TOPIC

15 June Joining Formalities

17 June General Introduction of NTPC & Power Scenario in India

18 June Economics of Power Generation

20 June Power Generation Process

21 June Safety Aspects in Power Plant

24 June Steam Turbine Auxiliaries-Intro. (CW/CT)

25 June Production of DM/ Clarified/ Softening of water and it’s quality control

27 June Plant Visit

29 June Evacuation of Power from Anta- Intro to 220 KV Switchyard

01 July Process Control & Instrumentation- STG/GT

04 July Electrical apparatus in Power Station and their Protection

05 July Plant Visit

08 July HR Structure & System

09 July Finance & accounting System

12 July Information Technology & communication Systems/ SAT System

14 July Distribution of certificates

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