industrial training report (genco-iii) by ( engr. ghias-ud-din)

INDUSTRIAL TRAINING REPORT

THERMAL POWER PLANT Gas turbine, Steam power & Central workshop

NOTHERN POWER GENERATION COMPAMY

LIMITED (GENCO-III), FAISALABAD.

SUBMITTED BY

GHIAS-UD-DIN

BSc ELECTRICAL ENGINEERING TECHNOLOGY

Session 2012-2016

2012-GCUF-01180

Roll no 1466

Training Report Period

15-02-16 to 24-05-16

DEPARTMENT OF ELECTRICAL ENGIEERING

GOVERNMENT COLLEGE UNIVERISITY

FAISALABAD

Industrial Training Report 2016

GHIAS-UD-DIN


GHIAS-UD-DIN

Dedication

I dedicate my dissertation work to my Family, thanks for their endless love, sacrifice,

prayers, supports and advices. I also dedicate this dissertation to my many friends and

class mates who have supported me throughout the internship. I will always

appreciate all they have done, especially Sir Maqbool, Sir Inam waris, Sir Muhammad

monas who Developed technology skills in me. I dedicate this work and give special

thanks to my University Teachers and HOD Engr. Ibrahim Khan.


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Acknowledgement

First of all I thanks to the Almighty ‘’ALLAH” who blessed me with courage and

made my efforts faithful, who best owed upon me with potential and ability to

contribute a little material to existing knowledge.

I pray all the tributes to the Holly Prophet Hazrat MUHAMMAD (S.A.W) who

enlightened our conscious, who is Torch of guidance and knowledge for humanity, all

and every respect is for the Holly Prophet Hazrat MUHAMMAD (S.A.W) who

enables us to recognize our creator.

I want to thanks the Chief Engineer (Thermal), Northern Power Generation Company

Limited (NPGCL) GENCO III, Faisalabad Mr. Sohail, Resident Engineer GTPS

Faisalabad, Resident Engineer Steam Power Plant Faisalabad, Resident Engineer

CGTM Workshop Faisalabad, Mr. Akbar, Assist. Director for their kind cooperation

during internship period. And Mr. Maqbool, Mr. Inam waris, Mr. M.Monas to

provided me the practical knowledge of the power plant, without their guidance and

help I could not completed my internship. I also like to thanks other Engineers and

staff of GENCO III (NPGCL) for their cooperation with me.

I would like to express my best regards to my academic coordinator, Professors,

Lecturers of Electrical Engineering Department, Govt. College University, Faisalabad

without of their guidance, I would not been able to complete my internship report

properly. Finally i want to thanks my Head of Department , Engr. M. Ibrahim khan.

I also want to thanks my group fellows Mr. Asad Ali, Mr. M.Waqar Arshad, Mr.

M.Usama Baig, Mr. Umer Virk, Mr. Zafer Iqbal, Mr. Mudasar and Mr. Mubasher to

share their knowledge and information with me and help me during the internship

period.

Signature of Student

Ghias-ud-din (1466)


GHIAS-UD-DIN

Training Certificate


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CERTIFICATE

I hereby certify that I have completed the Fourteen weeks Training in

partial fulfillment of the requirements for the award of BSc

ELECTRICAL ENGINEERING TECHNOLOGY. I did my training

in Nothern Power Genration Company Limited (GENCO-III), Faisalabad.

from 15-02-16 to 24-05-16.

The matter presented in this report has not been submitted by me for the

award of any other degree elsewhere.

Signature of Student

Ghias ud din (1466)

Examined by:

Engr. Rehan Liyaqat

INCHARGE/HOD

Engr. M.Ibrahim Khan

Electrical Engineering Department


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TABLE OF CONTENTS

Acknowledgement ………………………………………………………………….04

Training certificate …………………………………………………………………05

Table of Contents …………………………………………………………………...06

Chapter 1: Introduction ……………………………………………………………10

1.1 Industrial Background ………...…………………………………………………10

1.2 Products of Industry ……………………...……………………………………...10

1.3 Unit wise detail …………………………………...……………………………...10

1.4 Capacity ……………………………………………...…………………………..11

1.5 Company SWOT analyses ………………………………………...……………..11

Chapter 2: Parts of G.T Unit ………………………………………………………12

2.1 Machines Installed in the G.T. Plant …………………………………………….12

2.2 Main Parts ………………………………………..………………………………12

Chapter 3: Fuel ……………………………………………………………………..13

3.1 Fuel types ……………..…………………………………………………………13

Chapter 4: Air filter ………..………………………………………………………14

4.1 Inlet/outlet air Filter ………………………………………...……………………14

Chapter 5: Combustion chamber …………………………………………………15

5.1 Compressor ………………………………………………………………………15

5.2 Combustion chamber ……………………………………….……………………15

5.3 Liner ………………………………………………..……………………………16

5.4 Fish tail ……………………………………………………………..……………16

Chapter 6: Turbine …………………………………………………………...……17

6.1 Definition ………………………………………………………………………...17

6.2 Types ………………………………….…………………………………………17

6.3 Turbine start process …………………….………………………………………18

6.4 Process ……………………………………………….……..……………………18

Chapter 7: Generator ……………………………………………...………………19

7.1 Definition ……………………………...…………………………………………19

7.2 Parts of Generator ………………..………………………………………………19


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Chapter 8: Synchronize ……………………………………………………………20

8.1 Definition …………………...…………………………………………………20

8.2 Synchronization requirement ….………………………………………………20

Chapter 9: Combine cycle plant …………………………………………………...21

9.1 Working principle …………………………………………………………..…21

Chapter 10: Switchyard ……………………………………………………………22

10.1 Introduction …………………….………………………………………………22

10.2 Components & Devices used ..…………………………………………………22

10.2.1 Bus-bar ………………………………….……………………………………22

10.2.2 Bus Coupler ……………………………………..……………………………23

10.2.3 Feeder …………………………………………………………...……………23

10.2.4 CT/PT (Current and potential transformer) …..………………………………23

10.2..8 Power Transformer ……………………………..……………………………25

10.3 Parts of Transformer ……………………………………………………………26

10.4 Cooling system …………………………………………………………………26

10.5 Bucholz relay …………………………………………………………...………27

10.6 Relay ……………………………………………………………………………27

10.6.1 Relays types ……………………………..……………………………………27

10.6.2 Relay’s working ……………………………...………………………………27

Chapter 11: STEAM POWER PLANT ……………………...……………………28

11.1 Definition …………………………………………………………………….…28

11.2 Line diagram of Steam Power Plant ……………………………………………28

11.3 Basic parts of steam power plant ……………………………………………….28

11.3.1 Boiler …………………………………………………………………………28

11.3.1.1 Types of Boiler …………………………..…………………………………29

11.3.1.1.a Water Tube Boiler ……………..…………………………………………29

11.3.1.1.b Fire Tube Boiler ……………….…………………………………………29

11.4 Parts of Boiler …………………………………………………………………..30

11.4.1 Boiler drum …………………………………………...………………………30

11.4.2 Boiler furnace ………………………………………...………………………31

11.4.3 Burners ……………………………………………………….………………32

11.4.4 Super Heaters …………………………………………...……………………32

11.4.5 Re-heaters …………………………………………….………………………33

11.4.6 Boiler Water Tubes …………………………………..………………………33

11.4.7 Air pre-heater ………………………...………………………………………34

11.4.8 Forced Draught Fan …………………………………………….…………….34

11.4.9 Chimney / Stack ……………………………………………………………...34

11.4.10 Boiler Safety Valves ………………………………………………………...35

11.5 TURBINE ……………………………………………………………………....35

11.5.1 HP (High Pressure) Turbine ....……………………………………………….35

11.5.2 LP (Low Pressure) Turbine …………………………………………………..35

11.5.3 Specification of the steam turbine ……………………………………………36

11.6 DC Supply ……………………………………………………………………...36


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11.6.1 Importance of DC supply .………………………………………………….36

11.6.2 Different parts of DC supply ….……………………………………………36

11.7 Use of battery in power station ….……………………………………………37

Chapter 12: Cooling tower .………...……………………………………………...37

12.1 Definition ………………………………………………………………………37

12.2 Fan blades ………………………………………………………………………37

Chapter 13:CENTRAL G.T MAINTENANCE WORKSHOP …………………38

13.1 Workshop’s History …………...……………………………….…………….38

13.2 Maintenance workshops ……………………………………….……………..38

13.3 Cleaning shop ………………………………………………….……………..38

13.4 NDT shop …………………………………………………….………………39

13.5 Welding shop ………………………………………………………………...39

13.6 Grainding shop …………………………………….…………………………41

13.7 Bering re-metalling shop …………………………………….……………….42

13.8 Heat treatment shop ………………………………………………….……….43

13.9 Balancing shop ………………………………………………………….……43

13.10 Electrical Shop …………………………………………………………….44

13.11 Machine shop………………………………………………………………44

Skill attained ………………………………………………………………………..46

Recommendations ...………………………………………………………………..47

Abbreviations ...……………………………………………………………………..48


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CHAPTER 1- INTRODUCTION

1.1 Industrial Background

Northern Power Generation Company limited the largest generation company. Which

is worked in Muzzaffarghar (Genco-i), Multan (Genco-ii) And Faisalabad (Genco-iii).

The company produces electricity with thermal power. The power plant is establish in

1974 by AEG west German Company.

1.2 Products of Industry

Genco-iii is the bypass power plant. The power plant produces electricity by using the

natural gas/ HS Diesel, Furnace oil And exact steam.

1.3 Unit wise detail

SPS Faisalabad

UNIT

NAME

TYPE Date of

installing

Installed

Capacity

(MW)

Dependable

Capacity

(MW)

Fuel

Unit no 01 Steam

Turbine

11.06.1967 66 50 RFO/GAS

Unit no 02 Steam

Turbine

15.11.1967 66 50 RFO/GAS

GTPS Faisalabad

Unit

Name

Type Date of

installing

Installed

Capacity

(MW)

Dependable

Capacity

(MW)

Fuel

GT-1 Gas

Turbine

09.03.1975 25 21 GAS/HSD

GT-2 Gas

Turbine

10.03.1975 25 21 GAS/HSD

GT-3 Gas

Turbine

04.05.1975 25 21 GAS/HSD

GT-4 Gas 06.03.1975 25 21 GAS/HSD


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Turbine

GT-5 Gas

Turbine

31.07.1975 25 23 GAS/HSD

GT-6 Gas

Turbine

05.07.1975 25 23 GAS/HSD

GT-7 Gas

Turbine

10.07.1975 25 23 GAS/HSD

GT-8 Gas

Turbine

14.11.1975 25 23 GAS/HSD

GT-9 Combine

Cycle

28.12.1994 47 42 GAS/HSD

1.4 Capacity

The capacity of Genco-iii power plant is 247 MW (Gas turbine 200MW and Combine

Cycle 47 MW). And the SPS has two unit 132MW (66*2MW).

Turbine = 5000 RPM

Generator = 3000 RPM

Turbine = 25 M Watt 1*8

Combine cycle= 47 M Watt

1.5 Company SWOT analyses

STRENGTHS

The largest generation company.

Availability of land for capital expansion.

Power Plant are located in the load centers.

Highly qualified skilled Engineers and labor available.

Provision of Dual Fuel firing.

Road and Rail track facilities for furnace oil supply.


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CHAPTER 2- Parts of G.T Unit

2.1 Machines Installed in the G.T. Plant

Gas turbine power plant

2.2 Main Parts

Daily oil tank

Inlet/outlet air Filter

Compressor

Combustion Chamber

Turbine

Generator

Combine Cycle

Transformer

Combine cycle Inlet Filter Turbine Daily oil tank Generator


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CHAPTER 3- FUEL

3.1 Fuel types

(1) HSD oil (2) GAS

3.1.1 HSD OIL

The High speed Diesel (HSD) is used to operate the system. The daily tank used to

store the oil which is used in day. Its capacity is 5500 liters. Two filters are used to

purification the oil. And The A.C motor is used to flow the oil and D.C motor is used

as backup.

3.1.2 GAS

The Natural Gas is mostly used in system. The gas pressure should be 14-16kb. The

gas is mostly used due to cheap in price as compare to HSD.


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CHAPTER 4- AIR FILTER

4.1 Inlet/outlet air Filter

The Inlet/outlet Filter are specially developed for gas turbine compressors. The filters

are built to protect the gas turbine against pollution in the air and resist moisture. It

consists of 416 approx. and their use full life is around 2 years


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CHAPTER 5- COMBUSTION CHAMBER

5.1 Compressor

This compressor intakes air through air inlet filters and send it into combustion

chamber. The air passes through different stages and attains pressure & temperature.

On every stage the temp and Pressure rises with a specific ratio. Compressor has 16

stages and its comparison ratio is 1-10 bars. Thus if the inlet pressure is 1 bar then the

compressor outlet pressure will be 10 bar and temperature rises up to 450 ⁰C.

5.2 Combustion chamber

A combustor chamber is an area of gas turbine where combustion takes place. In the

combustion chamber the compressed air mixed with fuel and the mixture is burned.

Combustion chamber is a part of turbine where energy converts from chemical energy

into heat energy. Some gas turbines have 14 combustors and hot gases are passing

through each combustor and enter into turbine.


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5.3 Liner

The liners are used to control the fire in system. 8-10 liner used in each gas turbine.

The air is mixed with flame and burns the gasses.

5.4 Fish tail

The fish tail shape pipes are used to putt the hot gasses at the turbine to rotation.


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CHAPTER 6- TURBINE

6.1 Definition

A turbine is a machine that is designed to convert the chemical/fuel energy into

mechanical power. The 5100 rpm turbine used in the gas turbine.

6.2 Types

1. Impulse Turbine

2. Reactive Turbine

Parts of Gas Turbine

Filter House

Axial Flow Compressor

Combustion Chamber

Gas Turbine


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6.3 Turbine start process

Turbine start in different process

Check Ready to start Start Sequence in progress Auxiliarien ON

6.4 Process

The first 20% rotation of turbine is complete by the exciter generator or 350MW

motor. 20% to 60% of speed the flame accour which burn the furnace oil and the hot

gasses are produced to rotate the generator shaft.


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CHAPTER 7- GENERATOR

7.1 Definition

Generator is a machine which converted the mechanical energy in to the electrical

energy. The generator shaft is couple with turbine. The generator is 32 MVA. And

generate 11kv with 50 Hz frequency.

7.2 Parts of Generator:

Rotor & Stator

Casing & Bearing

Exciter

Rotor

This is rotating part of generator and field winding in nested upon it, this is coupled

with turbine shaft.

Stator

This is stationary part of generator and stator winding is nested in it, this is coupled

through bus bar to system.

Frame

Generator frame contain rotor winding, stator winding and bearing. Generator frame

restrict the outer element to get into the generator casing. This also prevents from

expulsion of hydrogen and provides heavy support.

Bearing

The bearing share load of generator rotor and prevent from excess radial movement.

Exciter

This device supplies DC current to rotor, so that the generator can work on the law of

electromagnetic.


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CHAPTER 8- SYNCHRONIZE

8.1 Definition

When two different electrical systems are coupled together it is called synchronization

or to connect the generator with system.

8.2 Synchronization requirement

There are three main aspects during synchronization

1. Generator and system voltage should be same.

2. Generator and system frequency should be same.

3. Generator and system phase angle should be equal.

For synchronize Automatic Voltage Regulator used for excitation.

Phase sequence, Voltage Level and frequency should same for synchronize.


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CHAPTER 9- COMBINE CYCLE PLANT

9.1 Working principle:

A combine cycle power plant is at the end of the gas turbine. This plant produce 50%

more electricity from the same fuel with the exact of 480’C, this exact is used into

combine cycle, and get 47 MW power in GTPS. The waste heat from the gas turbine

is used in boiler to produce the steam and this steam to rotate the steam turbine, the

turbine is coupled with generator shaft.


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CHAPTER 10- SWITCHYARD

10.1 Introduction:

Switchyard means collection of electrical equipment where high voltage electricity is

switched using of various component. Electrical switchyards are usually part of a

substation where electricity is transformed from one voltage to another for the

transmission or distribution.

Switchyard provides the facilities for switching, Protection & control of electric

power.

A switchyard is essentially a hub for electrical power sources. For instance, a

switchyard will exist at a generating station to coordinate the exchange of power

between the generators and the transmission lines in the area. A switchyard will also

exist when high voltage lines need to be converted to lower voltage for distribution

to consumers. The function of electrical switch yard is to deliver the generated power

from power plant at desired voltage level to the nearest grid. In Another way we can

say simply switching the received power supply from various generating stations to

various locations with respect to their requirement. Therefore a switchyard will

contain; current carrying conductors, grounding wires and switches, transformers,

disconnects, isolators, remotely controlled arc snuffing breakers, metering devices,

etc.

10.2 Components & Devices used in Switchyard

Bus bar

Bus couplers

Feeder

CT & PT

Power transformer

Isolators

Breakers

Lightening arrestor

10.2.1 Bus-bar

These are connecting bar which are connected to various local and distribution feeders

and also intact with supply sources. OR Those conductors that receive source supply


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and distribute to different lines.

10.2.2 Bus Coupler

Double bus scheme, where two bus bars are installed a provision of bus coupler has

been provided. Therein a bus coupling circuit breaker with two isolators is called bus

coupler. Its prime function is to substantiate the supply on any bus bar without

disconnecting with system.

10.2.3 Feeder

The feeder is used to connect the electricity to consumer. This has vital role is power

system

10.2.4 CT/PT (Current and potential transformer)

These are also called instrument transformer. These are used to measure voltage and

current of different high voltage lines.

CT is a type of instrument transformer that is used in power system for measurement,

detection, protection the system. Current transformers are used extensively for

measuring current and monitoring the operation of the power grid. Current

transformers, together with voltage transformers (VT) (potential transformers (PT)),

are known as instrument transformers.it is a device used to measure large current by

scaling large primary current to a smaller , easy to measure, secondary current.


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Current or voltage instrument transformers are necessary for isolating the protection,

control and measurement equipment from the high voltages of a power system, and

for supplying the equipment with the appropriate values of current and voltage -

generally these are 1A or 5Α for the current coils, and 120 V for the voltage coils.


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10.2.5 Isolator

Isolators are used in electrical substations to allow isolation of apparatus

such as circuit breakers and transformers, and transmission lines, for

maintenance. Often the isolation switch is not intended for normal

control of the circuit and is used only for isolation. This can be termed

as off load switch Isolator is also capable of switching with the charging

current and also breaks the bus transfer current which is its functional

requirement.

An isolator switch is used to make sure that an electrical circuit can be

completely de-energized for service or maintenance.

10.2.6 Breaker

A circuit breaker is an automatically-operated electrical switch designed to protect an

electrical circuit from damage caused by overload or short circuit. Its function is to

interrupt continuity, to immediately discontinue electrical flow. In switchyard High

Capacity Circuit Breakers are used. It works on on-load.

A circuit breaker is a piece of equipment which can

I. Make or break a circuit either manually or by remote control under normal

condition.

II. Break a circuit automatically under fault conditions

III. Make a circuit either manually or by remote control under fault condition

10.2.7 Lightening arrestor

A lightening arrester is a device to protect electrical equipment

from over-voltage transients caused by external (lightning) or

internal (switching) events. Also called a surge protection device

(SPD) or transient voltage surge suppressor (TVSS) .

A lightning arrester is a device used on electrical power systems

and telecommunication systems to protect the insulation and

conductors of the system from the damaging effects of lightning.

The typical lightning arrester has a high-voltage terminal and a

ground terminal. When a lightning surge (or switching surge,

which is very similar) travels along the power line to the arrester,

the current from the surge is diverted through the arrestor, in most

cases to earth.

10.2.8 Power Transformer

This is stationary device even though no part of this device is Rotating. This operates

on the law of mutual induction. According to Faraday’s law if current is supplied in


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one coil the due to mutual Induction the supply will automatically enters into second

coil. Transformer work on this law and transform the current from high to Low

voltage or low to high voltage. The coil in which the current is supplied called

“Primary coil” and the receiving coil is called “Secondary coil”. The transformer can

be step up or step down. Transformers are used to reduce of improve the generator

voltage which is further supplied to system.

10.3 Parts of Transformer

Parts of Transformer

Conservation tank

Breather

Primary winding

Secondary winding

LT terminal

HT terminal

Iron core

Transformer cover

Oil cooler

Cooling fans

Tap changer

10.4 Cooling system

ON,AN (oil natural, air natural)

ON,AF (oil natural, air forced)

OF,AF (Oil force, air forced)


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OF,AN (Oil force air natural

10.5 Bucholz relay

This relay has been installed in between conservator tank and transformer. This

prevent the transformer from every of kind of internal fault which can be occur by

short circuiting winding and core terminals. Due to short circuit the oil gets

overheated and resultantly gasification will occur. These gases travels to the

conservative tank thereby Bucholz relay has been placed. The mercury switches will

get operated which subsequently operate the primary and secondary circuit breaker

and generator breaker got opened. It is also called gas operated relay.

10.6 Relay

The relays are use for productions of the system

10.6.1 Relays types

The two type of relays are used .

1.Fix time relay

2.Inverse time relay

10.6.2 Relay’s working

The working of the relay depend on the signal of P.T and C.T, the D.C supply and the

time period. The relay should be healthy to product the system.

Relay using in R.E

Under excitation relay

Reverse power relay

Differential current relay

Generator over current relay

Condenser over current relay

Negative phase sequence

Earth fault/220 volt D.C fail

Generator winding temp high


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CHAPTER 11- STEAM POWER PLANT

11.1 Definition

A thermal power station is a power plant in which the prime mover is steam driven.

Water is heated, turns into steam and spins a steam turbine which either drives an

electrical generator.

11.2 Line diagram of Steam Power Plant

11.3 Basic parts of steam power plant

BOILER

TURBINE

GENERATOR

11.3.1 BOILER

A boiler or steam generator is a device used to produce steam by applying heat energy

to water. Thus, when heat is applied it produces steam and pressure in close vessel.


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11.3.1.1 Types of Boiler

Water tube boiler

Fire tube boiler

11.3.1.1.a Water Tube Boiler

In water tube boiler, boiler feed water flows through the tubes and enters the boiler

drum. The circulated water is heated by the combustion gases and converted into

steam at the vapor space in the drum. These boilers are selected when the steam

demand as well as steam pressure requirements are high.

11.3.1.1.b Fire Tube Boiler

In fire tube boiler, hot gases pass through the tubes and boiler feed water in the shell

side is converted into steam. Fire tube boilers are generally used for relatively small

steam capacities and low to medium steam pressures.


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11.4 PARTS OF BOILER

1. Boiler Drum

2. Boiler Furnace

3. Super Heaters

4. Re-heaters

5. Boiler water tubes

6. Air pre heater

7. F.D Fan

8. Chimney

9. Boiler safety valves

10. Down comers

11. Lower header / Drum

11.4.1 BOILER DRUM

Boiler drum receives feed water from economizer. This water goes through the drum

to down comers and thereafter it enters into up riser tubes. The up riser tubes generate

saturated steam which comes back into boiler drum and thereafter the steam goes to

different super heaters.


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Duties of Boiler Drum

1. Receives feed water

2. Store feed water

3. Distributes the water

4. Contains pressure

5. Receive steam water mixture

6. Provides outlet to saturated steam

7. It performs the process of separation and steam purification

8. At higher pressure with the aid of baffles and other devices.

11.4.2 BOILER FURNACE

The furnace is the place where burning process with a mixture of fuel and air takes

place. This provides space during burning. This also prevents the heat loss during fire

because this is a sealed compartment. Furnace disburses heat to up riser tubes which

converts water into steam. This also prevents to enter cold air into furnace.

The furnace design should be like that which prevent heat losses.


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11.4.3 Burners

Burner is a device, which helps to ignite fuel with the help of air. This device is used

for proper firing. Burner is a prime source to set right the fuel and air mixture,

pressure and firing location. Burner is also called boiler operating parameter due to its

importance for calculating boiler efficiency.

Properties of Burner

With the help of burner fuel burns completely.

Easy to operate.

Maintain fire arc’s direction, so that at heat utilized within furnace.

It makes proper mixture of air and fuel

11.4.4 Super Heaters

It is boiler auxiliary designed to superheat the saturated steam to a specified

temperature. It may reach up to 540 C.

Duties of Super Heater

1. It increases the temp. of saturated steam.

2. It is used to dry the steam

3. It provides an outlet to superheated steam towards the steam turbine.

Super heater consists of bundle of tubes from which saturated steam passes. This wet

steam gets more heat to convert into super-heated steam. Super heaters are installed in

all three zones of boiler.

1. Radiant Super heater

2. Platen Super heater


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3. Convective Super heater

The temperature of superheated steam is around 400 to 595 ⁰C. Usually it is around

540 ⁰C. The allowable difference is around ±5 to10 ⁰C

Advantage of super-heated steam

1. Improve turbine efficiency

2. No harm can occurred to turbine blade due to wet steam

3. No rust will occur to turbine blade

4. Blades do not bend

Steam temperature control in boiler

1. De-super heater

2. Gas recirculation fan

3. Fuel increased / decreased

4. Air flow control

5. Tilting of burner position

6. Soot blowing

7. Shot blasting

11.4.5 Re-heaters

Re-heater can also be termed as super heater. They can also be called as intermediate

super heaters. These are installed in flue gas duct. The get heat through flue gases and

rises wet steam temperature. There is no temperature different in re-heater or super

heater. However due no decrease in steam pressure it is called re-heater. The pressure

decreases due to line resistance.

Duties of re-heaters

1. Re-heaters increase the temperature of cold reheat steam

2. They prevent the condensation of steam in I.P turbine.

3. Re-heater is a safety device of I.P turbine.

11.4.6 Boiler Water Tubes

Down comers

Tubes that come downward from boiler are called down comers. These are located in

unheated zone. They contain feed water. Further due to less temperature of feed water

it become heavy comparison to steam, thus natural circulation of water occurs. The

feed water enters in boiler drum lower header. This is also called thermal circulation

of feed water.

Up riser

Tubes that come from downward to boiler drum called up risers. In these tubes water

coverts into saturated steam that why they are called as generation tubes. These tubes


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are located inside the furnace and came into radiation zone, that’s why they get

maximum heat. These are also called water wall and also used as insulation of boiler.

11.4.7 Air pre-heater

Heating combustion air can raise boiler efficiency about 1% for every 40⁰F in

temperature increase. The most common way to preheat the air is with a heat

exchanger on the flue exhaust. Air pre-heater is installed into flue gases duct. The

heating element get heat from flue gases and passes it to the air going into furnace, so

that temperature of combustion air increased. This helps for proper fuel burning.

11.4.8 Forced Draught Fan

This fan intake air from turbine hall or boiler side and sent it through air pre heater in

the burners. This creates a positive draught in furnace.

11.4.9 Chimney / Stack

A vertical channel or pipe which conducts smoke and combustion gases up from a fire

or furnace and typically through the roof of a building.

Chimneys are made of steel or masonry or common bricks or perforated bricks.

Generally they are made of several sections. For short exhaust stack, steel chimneys

are preferred. Steel chimneys are usually preferred in the case of GTPS because a gas

turbine attains its full load in less than a minute and as such a chimney has to with

stand, a thermal shock resulting from the increase in temperature of 450~500 0C

during this period.


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11.4.10 Boiler Safety Valves

The boiler drums are manufactured on a specific pressure. Thus, in case the pressure

exceed beyond the capability of boiler drum can explode and due to explosion,

chaotic situation can occur in shape of fatal accident to human or machinery. Thus, to

prevent from this state boiler safety valves are installed which operates on specific

pressure. So whenever pressure exceed from limit these valve get operated

automatically.

11.5 TURBINE

Turbine is used to convert the heat energy into mechanical energy.

The load requirement is controlled by the steam flow through a governing valve.

Steam turbine has two parts.

1. HP turbine

2. LP turbine.

11.5.1 HP (High Pressure) Turbine

First of all steam from boiler comes into the HP turbine. Steam in the HP turbine is

called live steam or main steam. Rotor blades diameter of this part of turbine is

smallest of the other parts of the turbine. Inlet steam temperature of the HP turbine is

950 F and pressure is 1250 Psi.

11.5.2 LP (Low Pressure) Turbine

The outgoing steam of the IP turbine entered into the LP turbine. Steam from the LP

turbine goes into the condenser.


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11.5.3 Specification of the steam turbine

Make Westinghouse USA

Maximum load 66MW each unit

Live steam pressure 1250 Psi

Live steam temperature 950 F

Rated speed 3000 rpm

Super heater Outlet Temp 950+10 F

11.6 DC Supply:

As we all know that AC supply can’t be stored. Thus the back systems in power

houses are used built on DC supply system. It is a stand by source of electricity

available at every movement in shape of storage batteries in order to protect our main

system to damage.

11.6.1 Importance of DC supply

All the control and protection system is based on DC supply. Usually the AC supply

is converted to DC through rectifier. Further battery bank is also used which is charge

through rectifier. This DC produced by battery bank is used in emergency when AC is

not available. Moreover, during charging the chemical energy converts into electrical

energy.

11.6.2 Different parts of DC supply

Rectifier

Battery charger

Battery cell 24VDC or 220VDC

11.7 Use of battery in power station

Control of electrical equipment/ Field flashing

Open / close of breakers

Position indicators/ Control and protection system

Emergency lights/ Emergency pumps


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CHAPTER 12- COOLING TOWER

Cooling tower

The cooling tower is used to cool the hot water. Which is used to cool the turbine,

generator and the boiler hot water.

Cooling Tower Fan Blades


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CHAPTER 13-

CENTRAL G.T MAINTENANCE WORKSHOP

13.1 Workshop’s History

This is the first and largest turbine maintenance workshop in Pakistan. The Workshop

is also involved in different maintenance/repair works for government and private

power plants. There are different kinds of machine using in the workshop for

repairing.

13.2 Maintenance workshops

Cleaning shop

NDT shop

Welding shop

Grainding shop

Bering re-metalling shop

Heat treatment shop

Balancing shop

Electrical shop

Instrument/Electronics shop

Chemical lab

13.3 Cleaning shop

The jobs which are the part of power plant accessories is treated cleaned first to

maintenance.

TYPES

Vapor decreasing

Vacuum blasting machine

Vapor blasting machine

Steam jet cleaner

Open dry blasting machine

Sand blasting machine


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13.4 NDT shop

The NDT stands for non- destructive test. In the shop we analysis and search

the crack in the job’s part. There are some methods used for the testing that can show

that place of the crack. The methods are describe below

Xyglo test check

Visual inspection

Penetrate test

Magnetic particle inspection

Ultrasonic test

Xyglo test set

This test is used to scan the job and mark the cracks in the internal and external sides

of the job body. This test is completed in following steps.

Chamber 01: Self emulsifying

Chamber 02: washing

Chamber 03: drying

Chamber 04: Developing powder

13.5 Welding shop

Welding types

Gas welding

Tig (argon) welding

Arc welding


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Gas welding

In this type of welding Oxyacetylene gases are used for welding.

Flame types

i. Natural flame [oxy (low) DS (low)]

ii. Carburizing flame [oxy (low) DS (high)]

iii. Oxidizing flame [oxy (high) DS (low)]

Flame parts

i. Inner core

ii. Envelop

Arc welding

Shielded Metal Arc welding is the process of joining two metal pieces using a flux

covered electrode which is melted in an electric arc.

Welding position

i. Flat G1 position

ii. Horizontal G2 position

iii. Vertical G3 position

iv. Over head G4 position

v. 180 degree G5 position

vi. 45 degree G6 position


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13.6 Grainding shop

Types

i. Strate grainding

ii. Angle pneumatic grainding

iii. Electric grainding

Cutter types

i. Stone cutter

ii. T-shape cutter

iii. Tree shape cutter

iv. Cylinder cutter

v. Ball cutter

vi. Flap wheel cutter

vii. Disk type


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13.7 Bering re-metalling shop

In General bearing the pads are made of white metal (nickel chromium + lead) first of

all the cracked metal melted using furnace after the removal of white metal to weld

the white metal on bearing pads surface should be neat and clean.


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13.8 Heat treatment shop

Heat treatment shop is used to heat the job/bearing to hardening the metals. In heat

treatment furnace resistive heating elements are used to heat the job.

13.9 Balancing shop

After the machine welding , grinding and machining turbine rotor should be balance

for that rotor bring to the balancing shop rotor is placed on the top of machine pads

prime mover moves the rotor balancing speed 200-250 rpm un balanced rotor spots

are shown on the computer screen then we weld a small wait on that sport


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13.10 Electrical Shop

Motor, generator are wounded In workshop, electrical faults of all machines in

workshop and all CT,PT’s switch gears, lights, motor starters & switch boards are

repaired.

13.11 Machine shop

Vertical lathe machine SC33

Chuck Diameter = 3300mm

Max Transverse = 2300mm

Max weight = 3500kg

Made in ROMANIA

Heavy Duty Machine (Rotor Balancing Machine)

Rotor weight = 2500-6000 kg

Max length of rotor= 8000 mm

Max Dia of rotor = 4000 mm

Rotor journal dia = 40-900 mm

Made in SCHENCK, GERMANY


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CNC lathe machine

Chuck Dia = 4000mm

Swing on BED = 4200mm

Length center to center= 15000mm

Job holding capacity = 100tons

Made in CHINA


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Skill attained

Complete start up of gas turbine processing.

Operation and maintenance work on 11kv switch gears V.C.B vacuum circuit

breakers.

Work on (A.C.B) air circuit breakers, (SF6) gas circuit breakers.

Maintenance & operation work on (M.C.R) master control room.

Maintenance work on motor starters (DOL) star delta & frequency control

invertors.

Over hailing & maintenance of three phase induction motors.

Maintenance of air conditioners.

Work on D.C motors and batteries.

Work on measuring instruments & transformers P.T & C.T.

Work in Cleaning shop, N.D testing shop, Welding shop and grinding shop.

Check all system and remove problems during running system.


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Recommendations

I found a very good practical learning environment at GENCO III (NPGCL). Some

recommendations are given for the students who want to do their internship program.

Undergraduate Internship Report Department of Electrical Engineering, Govt.

College University

Students must complete the courses related to their internship before

beginning the program. Completing the related courses before the internship

helps the students to understand the topic better.

During training period there may be any fault in the general activities of

power plant. It is necessary to learn about fault and how the engineers repair

the faulty part. Students should visit that faulty section and should try to get a

brief lecture on that fault from their mentor.


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Abbreviations

01 WAPDA Water and power development authority

02 AC Alternating current

03 CGTMW Central gas turbine maintenance workshop

04 CWP Circulating water pump

05 CT Current transformer

06 CNC Computer numeric calculation

07 DC Direct current

08 FD Force draft

09 FWP Feed water pump

10 GTPS Gas turbine power station

11 GENCO Generation company

12 HSD High speed diesel

13 HP HEATER High pressure heater

14 HP TURBINE High pressure turbine

15 HZ Hertz

16 HTV High tension voltage

17 LP TURBINE Low pressure turbine

18 LP HETAR Low pressure heater

19 LTV Low tension voltage

20 Lb. Pounds

21 NPGCL North power generation limited

22 NDT Non distractive test

23 OCB Oil circuit backer

24 PT Potential transformer

25 P.F Power factor

26 Psi Pressure stander international

27 RTD Resistance temperature detector

28 RPM Revolution per minute

29 SPS Steam power station

30 SF6 Sulfur hexa florid

31 SWG Stander wire gauge

32 TIG Tungsten inert gas

33 Tem. Temperature

34 VCB Vacuum circuit breaker

35 AVR Auto voltage regulator