Summer Project Report (Prakhar Gupta ,A2305106167)
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1 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
DCC PP
Submitted in partial fulfilment of the requirements
for the award of the degree of
Bachelor of Technology
In
Electronics & Communication Engg.
Supervisor: Submitted By:
Mr. H.P. SINGH Mr. PRAKHAR GUPTA
B.Tech ECE ,21008
Mrs. EILA SHARMA
AMITY SCHOOL OF ENGINEERING TECHNOLOGY, NOIDA
AMITY UNIVERSITY
UTTAR PRADESH
(2006-10)
2 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
CERTIFICATE
This is to cert ify that the dissertation enti t led “Familiarization with DCCPP”
is being submitted by PRAKHAR GUPTA (A2305106167) in partial fulfi l lment
for the award of the degree of Bachelor of Technology in Electronics and
Communication Engineering to the Amity University has been carried out by
them under our guidance and supervision. The results embodied in this thesis
have not been submitted to any other University or Insti tution for the award of
any other degree by them.
Date: Supervisor:
Mr. H.P. SINGH
Mrs. EILA SHARMA
3 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
ACKNOWLEDGEMENT
Setting an endeavor may not always be an easy task; obstacles are bound to come in its
way and when this happens, help is welcome and needless to say without help of those
people whom I am mentioning here, this endeavor would not have been successful.
My primary obligation is to Mr. S.B. GUPTA (Chief Engg.) who provided me the
opportunity and platform to undergo summer training in Dholpur Combined Cycle
Power Project (D.C.C.P.P.),DHOLPUR [Raj.]
During my project work many helping hands came across my way, I would like to
acknowledge my sincere and endless gratitude to them. First and foremost I express my
deep sense of gratitude to Mr. R.C. Meghwal (XEN Opr.) for his constant advice and
valuable time he has given to me for my project. They encouraged me to put forward my
best effort towards the completion of this project. I would also like to extend my special
thanks to Mr. S.B. Meena (XEn) and Mr. Gaurav(JEn) for his support at every step. I
am very much thankful to each and every member of DCCPP who helped me during the
course of training.
I am thankful from the core of my heart for the precious contribution of DG Mam, HOD
and faculty guides Mr. H.P. Singh and Mrs. Eila Sharma of ASET who provided their
best possible help. The successful completion of this training has been possible due to
sincere co-operation, guidance, inspiration, moral support and timely advice of each and
every one who devoted their utmost co-operation in this training.
PRAKHAR GUPTA
4 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
ABSTRACT
DCCPP is situated in the outskirts of Dholpur which is about 55Km.
South West of Agra. DCCPP is a Project of Rajasthan Rajya Vidhyut Utpada Nigam
Ltd.
The total estimated cost of the plant is Rs. 1155 crore. The main equipments were
supplied by M/s BHEL and it was also the main contractor for erection, testing and
commissioning of the plant. The BOP (Balance of plant) was given to M/s GEA Energy
System. The main fuel used for this plant is R-LNG (liquified natural gas) which will be
supplied by M/s GAIL. The gas required per day for both units is 1.3MM SCM at
9000Kcal.
The unique feature of this plant is that waste heat from the gas turbine is recovered by a
heat recovery steam generator to power a conventional steam turbine in a combined cycle
configuration. And also a MARK- 6 control system has been introduced for the first time
in the northern region in INDIA.
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CONTENTS
Chapter Title Page No.
Chapter 1. Introduction Of The Organisation
1.1 Dholpur Combined Cycle Power
Project (DCCPP) 10
1.2 Working Principle of Combined cycle
Power Plant 11
1.2.1 Method of Transforming other
power into electrical power 12
1.3 Selection of site for the Gas Power Plant 13
1.4 Features of the Plant 15
1.5 Plant Lay Out 17
Chapter 2. Gas Turbine (GT) 18
2.1 Working of Gas Turbine (GT) 19
2.2 Theory of Operation 20
2.2.1 Gas Power Cycle 21
2.2.2 Bray ton Cycle 21
Chapter 3. Heat Recovery Steam Generator (HRSG)
3.1 HRSG 26
3.2 Application of HRSG 28
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3.3 Component of HRSG 29
3.3.1 Economizer 30
3.3.2 Superheater 31
3.3.3 Evoporator 31
3.4 Salient Features of HRSG 32
3.5 Arrangement of HRSG DCCPP Plant 34
3.6 Working of HRSG 35
3.7 Specification of Boiler Drums 36
Chapter 4. Steam Turbine (ST) & Condenser
4.1 Steam Turbine (ST) 37
4.2 Advantages & Losses of ST 37
4.3 Working of ST 39
4.4 Condenser 40
4.5 Element of a Condensing Plant 41
Chapter 5. Combined Cycle Power Generation
5.1 Combined Cycle Electricity Generation 42
5.2 Advantages &Disadvantage. Of Combined
Power Plane 42
5.3 Classification of CCGPP 43
5.4 Environmental effect of Combined Cycle
Electricity Generation 43
5.5 Working of a CCPP 45
5.5.1 Power Generation 46
5.5.2 Emission Control 48
5.5.3 Transmission of Generated Power 49
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5.6 Water Tanks, Natural Gas Pipeline
& Control Room 50
Chapter 6. Water Clarification cum Filtration Plant & Turbo
Generator and Extation System
6.1 Water Clarification cum Filtration Plant 53
6.1.1 Various Process that are involved in
Treatment of Water 53
6.1.2 DeMineralizing Plant (DM Plant) 54
6.1.3 Degassifire 55
6.1.4 Weak base Anion Tank 55
6.1.5 Polishinging Unit 55
6.1.6 DM Water Quality 56
6.1.7 Water Softner 56
6.1.8 Analyzer DM Plant 56
6.1.9 CW Pump House 58
6.1.10 Water Classifier 58
6.2 Turbo Generator and Excitation System 59
6.2.1 Theory behind the working of a
Turbogenerator 59
6.2.2 Main Component of Generator 60
6.2.3 Functions of excitation System 60
6.2.4 Brushless Excitation System 60
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Chapter 7. 220KV Switchyard & Transformer and Maintenanc
Work
7.1 220KV Switchyard 62
7.1.1 Bus Scheme 62
7.1.2 Bus System 63
7.1.3 SF6 Gas Circuit breakers 63
7.1.4 Isolator 65
7.2 Transformers 65
7.2.1 Current and Capacitive voltage
Transformer 65
7.2.2 Lightning Arrestor and Arc Horns 65
7.2.3 Change over Schemes(Bus the Sys.) 65
7.2.4 Synchronization of the Generator
To the Grid 66
7.3 Maintenance Job to be Done on 220 KV Switchyard
7.3.1 Daily Job 67
7.3.2 Monthly Job 67
7.3.3 Quarterly Job 68
7.3.4 During annual ShutDown of Unit 70
Chapter 8. DC System & Power Line Communication
8.1 DC System 73
8.1.1 Batteries 73
8.1.2 Switchyard Building Battery bank 73
8.1.3 Battery Room 73
8.1.4 Electrolyte 74
8.1.5 Temperature Correction 74
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8.1.6 Normal operation of Batteries 74
8.2 Power line carrier Communication 75
8.2.1 Earth Shielding 75
8.2.2 Working 76
RESULT AND CONCLUSION 77
BIBLIOGRAPHY
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CHAPTER-1
INTRODUCTION OF THE ORGANISATION
1.1 DHOLPUR COMBINED CYCLE POWER PROJECT
DCCPP is situated in the outskirts of Dholpur which is about 55Km.
South West of Agra. Dholpur was considered an ideal location for setting up of a gas
power plant having regards to the availability of land, water, transmission network,
proximity to broad gauge railway , also well connected by roads (G.T. road passes
through this city) and being an important load center for eastern Rajasthan.
The total estimated cost of the plant is Rs. 1155 crore. The main equipments were
supplied by M/s BHEL and it was also the main contractor for erection, testing and
commissioning of the plant. The BOP (Balance of plant) was given to M/s GEA Energy
System. The main fuel used for this plant is R-LNG (liquified natural gas) which will be
supplied by M/s GAIL. The gas required per day for both units is 1.3MM SCM at
9000Kcal.
The unique feature of this plant is that waste heat from the gas turbine is recovered by a
heat recovery steam generator to power a conventional steam turbine in a combined cycle
configuration. And also a MARK- 6 control system has been introduced for the first time
in the northern region in INDIA.
A combined cycle is characteristic of a power producing engine or plant that employs
more than one thermodynamic cycle. Heat engines are only able to use a portion of the
energy their fuel generates (usually less than 50%). The remaining heat from combustion
is generally wasted. Combining two or more "cycles" such as the Brayton cycle and
Rankine cycle results in overall improved efficiency.
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In a combined cycle power plant (CCPP), or combined cycle gas turbine (CCGT) plant, a
gas turbine generator generates electricity and the waste heat is used to make steam to
generate additional electricity via a steam turbine; this last step enhances the efficiency of
electricity generation. Most new gas power plants in North America and Europe are of
this type. In a thermal power plant, high-temperature heat as input to the power plant,
usually from burning of fuel, is converted to electricity as one of the outputs and low-
temperature heat as another output. . As a rule, in order to achieve high efficiency, the
temperature difference between the input and output heat levels should be as high as
possible (see Carnot efficiency). This is achieved by combining the Rankine (steam) and
Brayton (gas) thermodynamic cycles. Such an arrangement used for marine propulsion is
called Combined Gas (turbine) And Steam (turbine) (COGAS).
1.2 WORKING PRINCPLE OF COMBINED CYCLE POWER PLANT
In a steam power plant water is the working medium. High pressure steam requires
strong, bulky components. High temperatures require expensive alloys made from nickel
or while the lower temperature of a stem plan is fixed by the boiling point of water.
With these cobalt, rather than inexpensive of steel. These alloys limit practical steam
temperatures to 655 ° limits, a steam plant has a fixed upper efficiency of 35 to 40%.
For gas turbines these limitations do not apply. Gas cycle firing temperatures
above 1,200 °C are practicable. So, a combined cycle plant has a thermodynamic
cycle that operates between the gas-turbine’s high firing temperature and the waste
heat temperature near the boiling point of water.
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1.2.1 Method for transforming other power in to electrical power :-
Rotating turbines attached to electrical generators produce most commercially available
electricity. Turbines may be driven by using steam. Water wind or other fluids as an
intermediate energy carrier. The most common usage is by steam in fossil fuel power
plants or nuclear power plants and by water in hydroelectric dams. Alternately turbines
can be driven directly by the combustion of natural gas.
Power plants are classified in the following categories according to the fuel used:
(a) Coal based thermal power plant
(b) Nuclear power plant
(c) Hydro electric power plant
(d) Solar power plant
(e) Wind power plant
(f) Gas power plant
Electricity From Natural gas :-
Power plant uses several methods to convert gas into electricity. One method is to burn
the gas in a boiler to produce steam, which is then used by a steam turbine to generate
electricity. A more common approach is to burn the gas in a combustion turbine to
generate electricity.
Another technology that is growing in a combustion turbine and used the hat combustion
turbine exhaust to make steam to drive a steam turbine. This technology is called
combined cycle and achieves a higher efficiency by using the same fuel source twice.
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1.3 SELECTION OF SITES FOR THE GAS POWER PLANT
1. SUPPLY OF WATER
A large quantity of water is required in steam power plants. It is required:
(I) It raises the steam in the boiler.
(II) For cooling purposes such as in condensers.
(III) As a carrying medium such as in disposal of ash.
(IV) For drinking purposes.
The efficiency of direct cooled plant is about 0.5% higher than that of the plant in which
cooling towers are used. This means a saving of about Rs. 7.5 lakhs per year in fuel cot
for a 2000 MW station
2. REQUIREMENT OF LAND
The land is required not only for setting up of the plant but also for other purposes such
as staff colonies, coal storage, ash disposal etc. cost of land adds to the final cost of the
plant. So it should be available at a reasonable cost. Land should be of good bearing
capacity since it has to withstand about 7 Kg. per Sq. Cm. Moreover, land should be
reasonably level. It should not be low lying.
3. TRANSPORTATION FACILITY
The land and rail connections should be proper and capable of taking heavy and over
dimensioned loads of machines etc. To carry coal, oil etc. which are daily requirements,
we need these transport linkages.
4. LABOUR SUPPLIES
Skilled and unskilled laborers should be available rates near the site the plant.
14 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
5. ASH DISPOSAL
Ash is the main waste product of the steam power plant. Hence some suitable means for
disposal of ash should be applied. Ash can be purchased by building contractors, cement
manufacturers or it can be used for brick making near the plant site. Otherwise wasteland
should be available near the plant site for disposal of ash.
6. DISTANCE FROM THE POPULATED AREA
Since most of the modern generating stations employ pulverized fuel residues and fumes
from them are quite harmful. Therefore the site for the plant should be away from the
populated area.
7. CLIMATIC CONDITIONS
Climate conditions of a place play a significant part in economics of capital investment.
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1.4 FEATURES OF THE PLANT
Two 250 MW Turbo-generator sets together with two boilers machine capacity along
with associate auxiliaries. The boilers are of natural circulation water tube single drum
pulverized fuel fired, dry bottom, balanced draft type using the direct firing system. The
steam turbines are of tandem compound operating on reheat and regenerating cycle and
condensing type. The turbo-generators. The cooling of stator is done by means of
Dimeneralized water and rotor by hydrogen. Brushless excitation system has been
provided.
TECHNICAL DATA:
1. COST OF THE PLANT Rs. 1155.15 Crore (STAGE-1)
2. DATE OF SYNCHRONIZATION:
UNIT 1 1sep2007__UNIT 2 1sep2007__UNIT 3 1 Jan 2008 __
3. CHIMNEY HEIGHT
Unit: 1, 2 220 Mt
4. WATER REQUIREMENT
400 m / hr (3 x 110m.w.)
16 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
BOILER
Type high pressure boiler drum
Capacity 780 tons/hr
Make BHEL
Steam Temperature 550 c
Steam Pressure 150 kg /cm2
GENERATOR Make Bhel
Type Tg -Hh-0250-2
Capacity 250mw
Kva 294100 Kva
Stator
Voltage 16,500 Volt
Current 10,290 Amp
Rotor
Voltage 319 Volt
Current 2386amp
Power Factor 0.85 Lag.
Speed 3000 Rpm
Frequency 50 Hz
Phase 3
Connection
Coolant Hydrogen
Gas Pressure 3 Bar
Insulation Class F
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1.5 PLANT LAY OUT
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CHAPTER-2
GAS TURBINE (GT)
A gas turbine extracts energy from a flow of hot gas produced by combustion of gas or
fuel oil in a stream of compressed air. It has an upstream air compressor (radial or axial
flow) mechanically coupled to a downstream turbine and a combustion chamber in
between. Gas turbine may also refer to just the turbine element.
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2.1 WORKING OF GAS TURBINE
DCCPP located at Dholpur has a unique feature that the same energy source (i.e. natural
gas) is used to rotate both gas and steam turbine without wasting much of energy. As the
name implies it is a combined cycle i.e. waste heat from the gas turbine is recovered by a
heat recovery steam generator to power a conventional steam turbine in a combined cycle
configuration. Hence, the working of both gas and steam turbine is discussed here.
A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy
from a flow of hot gas produced by combustion of gas in a stream of compressed air. It
has an upstream air compressor radial or axial flow mechanically coupled to a
downstream turbine and a combustion chamber in between. Gas turbine may also refer
to just the turbine element.
Energy is released when compressed air is mixed with fuel and ignited in the combustor.
The resulting gases are directed over the turbine's blades, spinning the turbine, and,
mechanically, powering the compressor. Finally, the gases are passed through a nozzle,
generating additional thrust by accelerating the hot exhaust gases by expansion back to
atmospheric pressure.
Energy is extracted in the form of shaft power, compressed air and thrust, in any
combination, and used to power electrical generators.
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2.2 THEORY OF OPERATION
Gas turbines are described thermodynamically by the Brayton cycle, in which air is
compressed isentropically , combustion occurs at constant pressure, and expansion over
the turbine occurs isentropically back to the starting pressure.
In practice, friction, and turbulence cause:
a) Non-isentropic compression: for a given overall pressure ratio, the compressor
delivery temperature is higher than ideal.
b) Non-isentropic expansion: although the turbine temperature drop necessary to
drive the compressor is unaffected, the associated pressure ratio is greater, which
decreases the expansion available to provide useful work.
c) Pressure losses in the air intake, combustor and exhaust: reduces the expansion
available to provide useful work.
21 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
2.2.1 Gas Power Cycle
although any cycle may in principle be used as a heat engine or as a refrigerator and heat
pump by just reversing the direction of the process in practice there are big difference and
the study is split between power cycle and refrigeration cycle.
Many gas cycle have been proposed and several are currently used to model real heat
engines. From the academic point of view we will the brayton cycle.
2.2.2 Bray ton Cycle:-
The Brayton Cycle nomad after the American engineer George bray ton is a good model
for the operation of a gas turbines engine. Now a days used by practically all aircraft
except the smallest once by fast boast and increasingly been used for stationary power
generation.
Particularly when both power and heat are of interest the ideal bray ton cycle in the T-S
and P-V diagram and the regenerative cycle. As with all cyclic heat engines, higher
combustion temperature means greater efficiency. The limiting factor is the ability of the
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steel, nickel, ceramic, or other materials that make up the engine to withstand heat and
pressure. Considerable engineering goes into keeping the turbine parts cool.
Most turbines also try to recover exhaust heat, which otherwise is wasted energy. the heat
released from the exhaust gas has been absorbed by many kms of tubing which line the
boiler. Inside these tubes is water, which takes the heat and is converted into steam at
high temperature and pressure. The type of boiler is called heat recovery steam
generation (HRSG) This steam at high temperature and pressure is sent to the turbine
where it is discharged through the nozzles on to the turbine blades.
The energy of the steam striking on the blades makes the turbine to rotate. Coupled to the
turbine is the rotor of the generator. So when the turbine rotates the rotor of the generator
turns. The rotor is housed inside a stator having heavy coils of copper bars in which
electricity is produced through the movement of magnetic field produced by the rotor.
Electricity passes from stator winding to the transformer, which increases its voltage
level so that it can be transmitted over the lines to far off places.
The steam, which has given away its energy, is changed back into water in the condenser.
Condenser contains many kms of tubing through which cold water is continuously
pumped. The steam passing over the tubes continuously loses heat and is rapidly changed
back into water. But the two waters i.e. the boiler feed water and cooling water must
never mix. Boiler water must be absolutely pure otherwise the tubing of the boiler may
get damaged due to the formation of salts inside the tubes due to the presence of different
impurities in water.
To condense large quantities of steam huge and continuous volume of water is required.
In some power stations same water has to be used again and again because there is not
enough water. So the hot water tracts are passed through the cooling towers. The cooling
23 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
towers are simply concrete shells acting as a huge chimney creating a draught of air. The
design of cooling towers is such that a draught of air is created in the upward direction.
The water is sprayed at the top of the tower. As it falls down the air flowing in the
upward direction cools it. The water is collected in a pond from where the water is
recirculated by the pumps to the condenser. Inevitably, however some of the water is
taken taken away by the draught of water in the form of vapours and it is this water with
familiar white clouds emerging from the cooling towers.
AnOther One:
Mechanically, gas turbines can be considerably less complex than internal combustion
piston engines. Simple turbines might have one moving part: the
shaft/compressor/turbine/alternator-rotor assembly (see image above), not counting the
fuel system.
As a general rule, the smaller the engine the higher the rotation rate of the shaft(s) needs
to be to maintain tip speed. Turbine blade tip speed determines the maximum pressure
that can be gained, independent of the size of the engine.
Thermal power station burn fuels and use the resultant steam to drive the turbo generator.
The object is to convert heat into mechanical energy in the turbine and to convert
mechanical energy into electrical energy by rotating magnets inside a set of magnets. The
coal brought to the station by means of trains travel from the coal handling plant by
conveyor belts to the coal bunkers. From where it is fed to pulverizing mills which grind
it to a fine powder. Finely powdered coal mixed with preheated air is blown into the
boiler by primary air fan where it burns more like a gas than as a solid with additional
amount of air called the secondary air supplied by the secondary draft fan.
24 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
As the coal has been ground finely the resultant ash is fine powder. Some of its contents
bind together to form lumps which fall in ash pits at the bottom of the furnace. The ash
mixed with water is then taken to the pits for subsequent disposal. The electrodes charged
by high voltage electricity in the electrostatic precipitator trap most of the ash. The dust is
then conveyed by water to the disposal area or to the bunkers while the cleaned flue gases
pass on through the ID fan to discharge through the chimney. Meanwhile the heat
released from the burning of coal has been absorbed by many kms of tubing which line
the boiler. Inside these tubes is water, which takes the heat and is converted into steam at
high temperature and pressure.
This steam at high temperature and pressure is sent to the turbine where it is discharged
through the nozzles on to the turbine blades. The energy of the steam striking on the
blades makes the turbine to rotate. Coupled to the turbine is the rotor of the generator. So
when the turbine rotates the rotor of the generator turns. The rotor is housed inside a
stator having heavy coils of copper bars in which electricity is produced through the
movement of magnetic field produced by the rotor. Electricity passes from stator winding
to the transformer, which increases its voltage level so that it can be transmitted over the
lines to far off places.
The steam, which has given away its energy, is changed back into water in the condenser.
Condenser contains many kms of tubing through which cold water is continuously
pumped. The steam passing over the tubes continuously loses heat and is rapidly changed
back into water. But the two waters i.e. the boiler feed water and cooling water must
never mix. Boiler water must be absolutely pure otherwise the tubing of the boiler may
get damaged due to the formation of salts inside the tubes due to the presence of different
impurities in water.
25 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
To condense large quantities of steam huge and continuous volume of water is required.
In some power stations same water has to be used again and again because there is not
enough water. So the hot water tracts are passed through the cooling towers. The cooling
towers are simply concrete shells acting as a huge chimney creating a draught of air. The
design of cooling towers is such that a draught of air is created in the upward direction.
The water is sprayed at the top of the tower. As it falls down the air flowing in the
upward direction cools it. The water is collected in a pond from where the water is re-
circulated by the pumps to the condenser. Inevitably, however some of the water is taken
away by the draught of water in the form of vapours and it is this water with familiar
white clouds emerging from the cooling towers.
26 | P a g e Familiarization with DCCPP (Dholpur Combined Cycle Power Project )
CHAPTER-3
HEAT RECOVARY STEAM GENERATOR (HRSG)
3.1 HRSG
A heat recovery steam generator or HRSG is a heat exchanger that recovers heat from a
hot gas stream. It produces steam that can be used in a process or used to drive a steam
turbine. A common application for a HRSG is in a combined-cycle power station, where
hot exhaust from a gas turbine is fed to an HRSG to generate steam which in turn drives a
steam turbine. This combination produces electricity more efficiently than either the gas
turbine or steam turbine alone. The HRSG is also an important component in
cogeneration plants. Cogeneration plants typically have a higher overall efficiency in
comparison to a combined cycle plant. This is due to the loss of energy associated with
HRSGs consist of three major components. They are the Evaporator, Superheater, and
Economizer. The different components are put together to meet the operating requirements of the
unit. See Modular HRSG GA.
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Modular HRSGs normally consist of three sections: an LP (low pressure) section, a
reheat/IP (intermediate pressure) section, and a HP (high pressure) section. Each section
has a steam drum and an evaporator section where water is converted to steam. This
steam then passes through superheaters to raise the temperature and pressure past the
saturation point.
Packaged HRSGs are designed to be shipped as a fully assembled unit from the factory.
They can be used in waste heat or turbine (usually under 20MW) applications. The
packagaged HRSG can have a water cooled furnace which allows for higher
supplemental firing and better overall efficiency.
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Some HRSGs include supplemental, or duct, firing. These additional burners provide
additional energy to the HRSG, which produces more steam and hence increases the
output of the steam turbine. Generally, duct firing provides electrical output at lower
capital cost. It is therefore often utilized for peaking.
HRSGs can also have diverter valves to regulate in the inlet flow into the HRSG. This
allows the gas turbine to continue to operate when there is no steam demand or if the
HRSG needs to be taken offline.
Emissions controls may also be located in the HRSG. Some may contain a Selective
Catalytic Reduction system to reduce nitrogen oxides (a large contributor to the
formation of smog and acid rain) and/or a catalyst to remove carbon monoxide. The
inclusion of an SCR dramatically affects the layout of the HRSG. NOx catalyst performs
best in temperatures between 650°F and 750°F. This usually means that the evaporator
section of the HRSG will have to be split and the SCR placed in between the two
sections. Some low temperature NOx catalysts have recently come to market that allows
for the SCR to be placed between the Evaporator and Economizer sections (350°F-
500°F).
3.2 APPLICATIONS OF HRSG
Heat recovery can be used extensively in energy projects.
In the energy-rich Persian Gulf region, the steam from the HRSG is used
for desalination plants.
Universities are ideal candidates for HRSG applications. They can use a gas
turbine to produce high reliability electricity for campus use. The HRSG can recover
the heat from the gas turbine to produce steam/hot water for district heating or
cooling.
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3.3 COMPONENT & ARRANGEMENT OF HRSG
There are two boiler drums in HRSG-
1.High pressure drum
2.Low pressure drum
There are deviation in boiler drums . Steam accumulated in upper part of drum water in
the lower part of the drum water is drawn out by a pipe at the bottom of the drum
If there are excess pressure and temperature. Then to remove these there are two
controlling arrangements
1.Pressure controlling arrangement.-pressure safety valves like pressure cooker
whistle loaded there and design to release excess pressure.
2.temprature controlling arrangement-a “D”shape pipe is there for control the
excess temp. If temp. exceed demineralized water is sprayed in it. And the temp.
lowered
There are two HRSG plant for two gas turbine.
The combined steam of HRSG-1& HRSG-2 produce the power of 110MW.
In a boiler drum there are riser pipes. from which steam comes into the drum.
HP drum is bigger then LP drum
There are three main components of HRSG
1.Economisers
2.superheaters
3.evoporator
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3.3.1 Economiser
The greatest item of heat loss in a boiler plant is that pf the heat is carried away in the
flue gases of the chimney stack. some of this heat may be recovered and sent back into
the boiler in the feed water by an economizer a saving of 10 percent.
The advantage of economizer are
1. increase the efficiency of boiler plant
2. reduce the range of temp.b/w different parts of boiler and hence reduces the stress
due to unequal expansion
3. more rapid evaporation and hence quicker circulation of water making the heating
surface increase the efficiency of boiler plant
4. reduce the range of temp.b/w different parts of boiler and hence reduces the stress
due to unequal expansion
5. more rapid evaporation and hence quicker circulation of water making the heating
more effective
Disadvantage of economiser
1. there is a loss of draught for the flue gases and natural draught is un sufficient. the
plant has to provided with an artificial draught equipment
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3.3.2 Superheater
A superheater is a device used to convert saturated steam into dry steam used for power
generation or processes. There are three types of superheaters namely: radiant,
convection, and separately fired. A superheater can vary in size from a few tens of feet to
several hundred feet (a few meters or some hundred meters)
It is surface heat exchanger in which the heat of the combustion product is utilized first
to dry wet steam and then to raise the temp. in super heater there is no change of pressure
of steam but its volume increased and temp is raised.
3.3.3 Evoporator
Within a downstream processing system, several stages are used to further isolate and
purify the desired product. The overall structure of the process includes pre-treatment,
solid-liquid separation, concentration, and purification and formulation. Evaporation falls
into the concentration stage of downstream processing and is widely used to concentrate
foods, chemicals, and salvage solvents. The goal of evaporation is to vaporize most of the
water from a solution containing a desired product. After initial pre-treatment and
separation, a solution often contains over 85% water. This is not suitable for industry
usage because of the cost associated with processing such a large quantity of solution,
such as the need for larger equipment
Evoporator-in this phase change is done .in this water change into steam
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3.4 SALIENT FEATURES OF HRSG
Horizontal Natural Circulation Design.
Steam generation at multiple pressure levels with or without reheaters.
Modular construction with spiral finned tubes for compactness.
Fully drainable heat transfer section
Short installation time.
Ease of operation.
Supplementary Fuel firing system to meet specific customer requirements.
o -In duct firing/Furnace firing.
o Multiple Fuel firing (Oil/Gas).
Low NOx and CO emission.
o Stand by fresh air firing with FD fan for uninterrupted steam supply ( FD
Fan mode ).
Unfired boiler.
Exhaust gases are used to generate steam.
500 c lower portion.
High pressure circuit two.
6H bar upper portin economizer.
Low temperature portion.
6 bar 202 c (ragging)
Discharge pressure 1H bar steam
Water tube boiler.
Forced circulation boiler.
Vertical boiler.
At 100 c leaver boiler.
Deareater feed storage tank
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Circuit feed regulating
Economizer station controls
Evaporator flow
Super heater H.P. turbine and L.P. turbine
Twin cyclender turbine.
Tendon compound turbine.
HP STEAM (RATED PARAMETERS)
• PRESSURE : 78.2 Kg/Cm2.
• TEMPERATURE : 514+/- 5 Deg. C
• FLOW : 187.1 TPH.
LP STEAM (RATED PARAMETERS)
• PRESSURE : 5.0 Kg/Cm2.
• TEMPERATURE : 200 Deg. C
• FLOW : 39.8 TPH.
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3.5 ARRANGEMENT OF HRSG DCCPP PLANT
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3.6 WORKING OF HRSG
In this the water used in steam generation is de mineralized water .because steam of DM
water not contains any particles and minerals. If these substances present in steam it may
be harmful for turbine blades.
From a water reservoir water is supplied in water clarifier .then supplied in DM plant in
which water is undergoes too many chemical reactions with diff. chemicals to remove its
impurities & minerals after which is supply to the plant.
First of all dm water comes in economizer so that increase the temp. of water. in this the
hot flue gases passes over exterior of tubes. heating of feed water by 1deg.c permits
reducing the temp. of flue gases by 2to3 deg. By this efficiency of boiler is increased.
After this water is supplied to boiler drum then evaporator. In this water is converted into
steam. this steam is wet steam. then this steam passes through superheaters to raise the
timpani pressure past the saturation point. by this dry steam is getting after this steam is
supplied to boiler drum and then steam turbine.
Wet steam may be harmful to turbine blades. So superheated steam is used to turbine.
There are so many modules of components of HRSG. These are alloy steal pipes
surrounded by small fins in which water flow for heating purpose .and these fins are used
for heat transfer and cooling of pipes,
These modules are a type of heat exchanger where heat exchange takes place b/w DM
water & exhaust of turbine.
Boiler drums are made by mild steel . because of its ductility.
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3.7 SPECIFICATION’S OF BOILER DRUMS
1. HP DRUM :
Design pressure 105kg/ cm2
Working pressure 78.2kg/ cm2.
Hydraulic pressure 157.5kg/ cm2
Water temperature ambient
Holding time 10 min.
HP steam 79.8kg/cm2
Steam temp 490°c
2. LP DRUM:
Design pressure 12kg/ cm2.
Working pressure 05 kg/ cm2
Hydraulic pressure 18kg/ cm2
Water temp. ambient
Holding time 10 min.
Steam temp. 220°c
3. CHIMENY EXHAUST:
Maximum temperature 90°c
Working temperature 65-70°c
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CHAPTER-4
STEAM TURBINE (ST) & CONDESER
4.1 STEAM TURBINE
In a steam turbine steam is passed through nozzles or fixed blades where the heat drops
takes place increasing the velocity of steam. the high velocity steam impinges on the
curved vanes which causes the directions of the steam to be changed. Due to this change
of momentum motive force is exerted on the moving blades and power is obtained.
4.2 ADVANTAGE OF STEAM TURBINE
1. the thermodynamic efficiency of steam turbine is higher than that of steam engine
because these work on Rankine cycle whereas steam engine works on modified
Rankine cycle. A steam turbine can thus take advantage of expansion up to the
lowest pressre. the lowest exhaust pressure of steam turbine is as low as 2.5cm
hg(.035 bar)whereas in steam engines it is 15 to 20cm of hg(.2to.3bar)
2. the mechanism is simple as inter mediate links like piston, piston rods, croos
head, etc, are absent.
3. there is no initial condensation as the parts are subjected to constant temp. and at
constant loads.
4. power is generated uniform rate ,hence no fly wheel is necessary.
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5. no internal lubricant is necessary, which reduce the cost of lubrication and
supplies a purer feed to the boiler.
6. due to absence of reciprocating parts, perfect balance is possible which avoids
heavy foundations.
7. steam turbine can carry considerable overloads with only a slight reduction in
efficiency.
8. the thermal efficiency of steam turbines plants is 35to40%, whereas for steam
engine it is 15to 20 %.
LOSES IN STEAM TURBINE
1. Loss in the exit velocity of steam: The loss in the exit velocity of the steams due
to blade efficiency not being 100percent.this is because of the obliquity of
nozzles. if the nozzle angle is zero, blade efficiency would be 100 percent.
2. Loss due to friction and turbulence: Friction occurs in nozzles and blades and b/w
steam and rotating disc. also due to centrifugal action steam is thrown radially
towards the casing and dragged along the surface by the moving blades. these
losses are called the disc friction and wind edge losses.
3. Loss due to leakage: In impulse turbine leakage occurs b/w the shaft and the
stationary diaphragms carrying nozzles. in the reactions turbine the leakage is at
the blade tips.
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4. Losses due to mechanical friction to the bearing , etc. this loss is less then 1 %
and it decreases with the size of the plant.
5. Losses due to radiation is negligible.
6. Governer losses: it is due to throttling. This may in order to 5to10%.
7. Exhaust losses: the steam leaves the turbine with a finite. Absolute velocity which
is partially or wholly lost.
In this plant steam turbine produces 110MW electricity, running by combined steam of
HRSG. so in this plant cost of coal handling and ash handling is negligible.
4.3 WORKING OF STEAM TURBINE
The steam turbine is a Siemens Westinghouse KN Turbine Generator, capable of
producing up to 240 MW. It is located on top of the condenser, across from the
cooling tower.
Steam enters the turbine with temperatures as high as 1000 degrees Fahrenheit
and pressure as strong as 2,200 pounds per square inch. The pressure of the steam
is used to spin turbine blades that are attached to a rotor and a generator,
producing additional electricity, about 100 megawatts per HRSG unit.
After the steam is spent in the turbine process, the residual steam leaves the
turbine at low pressure and low heat, about 100 degrees. This exhaust steam
passes into a condenser, to be turned back into water.
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By using this “combined-cycle” process, two gas turbines and one steam turbine,
we can produce a total of about 110 megawatts of electricity.
4.4 CONDESER
The purpose of the condenser is to turn low energy steam back into pure water for
use in the Heat Recovery Steam Generator
A condenser makes it possible to remove exhaust economically at a pressure less
then that of atmosphere . thus by use of an condenser in a steam plant low exhaust
pressure can be used and large heat drop per kg of steam utilized increasing both
the efficiency and power output of the plant.
ADVANTAGE:
Hot feed water at 40°c to 50°c is available for returning to the boiler.
Air and non condensable gases , which have corrosive action, are removed.
Recovery of condensate reduce the make up water that must be added to the
system.
Where the feed water available is not pure , recovery of condensate reduce the
capital and running cost of the water softening plant.
In a condenser , absolute vacuum is neither possible nor economical to maintain . beside
enormous increases in the condenser size a higher vacuum result in lower temperature of
the condensate returned to the boiler and increase in the rate of flow of cooling water and
consequently the power required to derive the circulating pumps.
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4.5 ELEMENT OF A CONDENSING PLANT
1. The condenser where steam is condensed.
2. The condensate pump for extracting water for the condenser to the hot well.
3. The hot well for collecting the condensate.
4. The air ejector or dry air pump for removing the non condensable gases from the
condenser.
5. The circulating water pump for circulating the cooling water.
6. The cooling tower if same circulating water is to be used again and again.
sometime the term hot well is applied to the collection space at the bottom of condenser
and the hot well is termed “surge tank”
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CHAPTER-5
COMBINED CYCLE POWER GENERATION
5.1 COMBINED CYCLE ELECTRICITY GENERATION
Growth in gas fueled combined cycle system will take place, Because of the attractive
economic environmental and operating characteristics of this natural gas system .
Combined cycle gas turbine plants generate electricity more. Efficiently than
conventional fossil to percent compares with 30 to 50 percent for typical now biological
units.
5.2 Advantage of Combined Cycle Gas Power Plant
High Thermal Efficiency
Low water Requirement
Environmental friendliness
Fast start-up
Low Gestation period
Low Installation Cost
Disadvantage of Combined Cycle Gas Power Plant
Low thermal Efficiency in Open cycle
Higher Cost of Generation
Higher Maintenance Cost
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5.3 Classification of Combined Cycle Gas Power Plant
SIZE PLANT CAPACITY GT CAPACITY
SMALL UP-TO 100 MW 30-40 MW
MEDIUM 150-400 MW 60-120 MW
LARGE > 400 MW > 120 MW
5.4 Environmental effects of combined cycle electricity generation
(a). Natural-gas fueled combined cycle units are environmentally performable to
conventional coal system the gas combined cycle unit produces none of the solid waste
associated with coal units less than 1 percent of the sulfur dioxide and particulate matter
and about 85 percent less nitrogen oxide produces by a similarity sized new coal unit
equipped with pollution control equipments.
(b). Cogeneration System :- Cogeneration is use of a primary energy like natural gas to
sequentially produce heat and electricity. The concept is based on the recover and use of
waste heat produced daring the generation of electricity. In most electric utility power
plants. This waste heat is lost resulting in substantially lower operating efficiencies than
with cogeneration.
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A variety of natural gas cogeneration technologies are currently being used. Including
small prepackaged units that incorporate all the necessary components for a cogeneration
system as well as high efficiency industrial gas turbines. These natural gas cogeneration
system are available in sizes ranging from as small as 202 kw to as larges as several
hundred mega watts.
(c.) Air Emissions :- The average emissions rates in the united states from natural gas
fired generation are 1135 ibd/meh of carbon dioxide 0.1 ibs/mwh of sulfer dioxide and
1.7 ibs/mwh of nitrogen oxide compared to the average air emissions from coal fired
generation natural gas produces as much carbon dioxide less than a third as much
nitrogen dioxide at the power plant in addition the process of extraction treatment and
transport of the natural gas to the power plant generators additional emissions.
(d) Design Principle :- in a gas turbine set composed primarily of a compressor burner
and the gas turbine proper. The input temperature to the gas turbine is relatively high but
the output temp of the fuel gas temperature is sufficient for production of steam in the
second steam cycle with live steam temperature in the range of steam cycle depends on
the ambient temperature and the methods of waste heat disposal either by direct cooling
by lake river or sea water or using cooling towers.
(e) Efficiency of CCGT Plants :- The thurmel efficiency of a combined cycle power
plant is normally in termsof the net power output of the plant as a percentage fo the lower
heating value or net calorific value of the fuel. In the case of generating only etc. criticity
power plant efficiencies of up to 59% can be achieved in the case of combined heat and
power generation the efficiency can increase to about 85%.
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5.5 WORKING OF A COMBINED CYCLE POWER PLANT
DCCPP located at Dholpur has an unique feature that the same energy source (i.e. natural
gas) is used to rotate both gas and steam turbine without wasting much of energy. As the
name implies it is a combined cycle i.e. waste heat from the gas turbine is recovered by a
heat recovery steam generator to power a conventional steam turbine in a combined cycle
configuration.
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5.5.1 Power Generation:
1) Air Inlet
The amount of air needed for combustion is 800,000 cubic feet per minute. This
air is drawn though the large air inlet section where it is cleaned, cooled and
controlled, in order to reduce noise.
2) Two Siemens Westinghouse 501FD Turbine-Generators:
The air then enters the gas turbine where it is compressed, mixed with natural gas
and ignited, which causes it to expand. The pressure created from the expansion
spins the turbine blades, which are attached to a shaft and a generator, creating
electricity.
Each gas turbine produces 185 megawatts (MW) of electricity.
The blades are attached to a rotor, which spins the generator, and makes
electricity. Think of a generator as a huge spinning magnet inside a coil of wire.
As the magnet spins, electricity is created in the wire loops.
3) Heat Recovery Steam Generator (HRSG)
The hot exhaust gas exits the turbine at about 1100 degrees Fahrenheit and then
passes through the Nooter Erickson, Heat Recovery Steam Generator (HRSG).
In the HRSG, there are 18 layers of 100-foot tall tube bundles, filled with high
purity water. The hot exhaust gas coming from the turbines passes through these
tube bundles, which act like a radiator, boiling the water inside the tubes, and
turning that water into steam. The gas then exits the power plant through the
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exhaust stack at a much cooler 180 degrees, after having given up most of its heat
to the steam process.
About 1 million pounds of steam per hour is generated in this way and sent over
to the steam turbine through overhead piping.
4) Steam Turbine
The steam turbine is a Siemens Westinghouse KN Turbine Generator, capable of
producing up to 240 MW. It is located on top of the condenser, across from the
cooling tower.
Steam enters the turbine with temperatures as high as 1000 degrees Fahrenheit
and pressure as strong as 2,200 pounds per square inch. The pressure of the steam
is used to spin turbine blades that are attached to a rotor and a generator,
producing additional electricity, about 100 megawatts per HRSG unit.
After the steam is spent in the turbine process, the residual steam leaves the
turbine at low pressure and low heat, about 100 degrees. This exhaust steam
passes into a condenser, to be turned back into water.
By using this “combined-cycle” process, two gas turbines and one steam turbine,
we can produce a total of about 110 megawatts of electricity.
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5.5.2 Emissions Control
1) Selective Catalytic Reduction (SCR)
To control the emissions in the exhaust gas so that it remains within permitted
levels as it enters the atmosphere, the exhaust gas passes though two catalysts
located in the HRSG.
One catalyst controls Carbon Monoxide (CO) emissions and the other catalyst
controls Oxides of Nitrogen, (NOx) emissions.
2) Aqueous Ammonia
In addition to the SCR, Aqueous Ammonia (a mixture of 22% ammonia and 78%
water) is injected into system to even further reduce levels of NOx.
3) Best Available Control Technology (BACT)
Our annual average concentration of NOx is only 2 parts per million, which is
considered the “best available control technology” or BACT by the Air Board.
As exhaust gas passes out of the exhaust stack, it is continuously sampled and
analyzed, assuring that permit limits are being met.
With this kind of clean, modern technology, the exhaust stack is only 145 feet
high, compared to 500 feet, the height required by older power plants that use less
efficient emission technology.
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Environmental and health organizations recognize this technology as a benefit to
the community. The local chapters of the American Lung Association and Sierra
Club both support the Metcalf Energy Center.
5.5.3 Transmission of Generated Power onto the Grid
1) Transformers
The Gas Turbine and Steam Turbine generators produce power at 13,000 volts.
The transformers take the generated 13,000 volts and “transform” them to
230,000 volts, which is the required voltage needed for transmission to the nearby
tower that sends power to the substation.
A small amount of generation is directed to “Auxiliary transformers” which
“transform” the generated voltage to a lower voltage, so it may be used by the
plant to power our own pumps, fans, and motors. The Metcalf Energy Center
requires 12 – 15 megawatts to operate.
2) Switchyard
From each transformer, the power passes underground into our switchyard. The power from all
of the generators comes together there, where it is measured, metered and directed onto the
grid.
The proximity of the site to a large, existing PG&E substation makes it a good
place to build a power plant and the nearest transmission tower is only about 200
feet away.
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3) Condenser and Cooling Tower
The purpose of the condenser is to turn low energy steam back into pure water for
use in the Heat Recovery Steam Generator.
The purpose of the cooling tower is to cool the circulating water that passes
through the condenser. It consists of ten cells with large fans on top, inside the
cone-like stacks, and a basin of water underneath.
We process and treat the Title 22 recycled water after receiving it from the City,
before using it in our cooling tower. The cool basin water absorbs all of the heat
from the residual steam after being exhausted from the steam turbine and it is then
piped back to the top of the cooling tower.
As the cool water drops into the basin, hot wet air goes out of the stacks.
Normally, hot moist air mixes with cooler dry air, and typically a water vapor
plume can be formed, one that may travel hundreds of feet in the air and be seen
from miles away. The California Energy Commission considered this visually
undesirable in this community so we added a “Plume-Abatement” feature, louvers
along the topsides of the tower that control the air flow.
The cooling tower evaporates about three-fourths of the processed, recycled
water, then we send about one-fourth of it back through the sewer lines for re-
treatment by the City.
The Metcalf Energy Center purchases 3 to 4 million gallons per day of recycled
water from the City of San Jose. Evaporation of this water assists the City in
adhering to their flow cap limits and helps to protect the sensitive saltwater marsh
habitat of the San Francisco Bay environment from receiving too much fresh,
recycled water.
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5.6 Water Tanks, Natural Gas Pipeline, Control Room
1) Water Tanks
The largest tank is the Service Water tank. It contains 470,000 gallons of water to
be used for drinking, fire fighting and for the high purity water train. The water
from the service water tank is pumped to the water treatment building where it
then passes through a reverse osmosis unit, a membrane decarbonater, and mixed
resin bed demineralizers to produce up to 400 gallons per minute of ultra pure
water.
The pure water is then stored in the smaller 365,000-gallon tank until it is turned
into steam for making electricity.
2) Natural Gas
Natural gas fuels the combustion turbines. Each turbine can consume up to 2,000
MMBTU per hour.
The fuel comes from the major high pressure natural gas pipeline that runs along
the east side of Highway 101, less than 1 mile to the east of our site.
During construction, “Horizontal Directional Drilling” was utilized with careful
coordination with many local authorities. The pipeline was built 60 feet
underground and passed under highways, creek, train tracks, and environmentally
sensitive areas.
The pipeline enters the site just behind the water tanks, where equipment
regulates and measures the natural gas composition, flow and pressure.
Gas compressors pump the natural gas though the facilities’ fuel gas system
where it is delivered to the gas turbine and the HRSG duct burners at the proper
temperature, pressure and purity.
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3) Control Room
From the control room, the plant operators monitor and operate the facility, via
the plant’s “Distributed Control System”, with the click of a mouse, viewing
graphic representations of all MEC systems on various screens.
The system gives operators both audible and visual signals to keep them informed
of plant conditions at all times and to determine when preventative maintenance is
required.
CONTROL ROOM
WATER TANK
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CHAPTER-6
WATER CLARIFICATOIN CUM FILTRATION PLANT &
TURBO-GENERATOR AND EXCITATION SYSTEM
6.1 WATER CLARIFICATOIN CUM FILTRATION PLANT
The source of water to the power station is from across river Chambal .the total water
requirement for the capacity 330 MW is estimated at 850 cusses . the river water contains
different impurities-
Suspended Impurities – Removed by Al, Cl2 , Co(OH) 2 where alum is used to
coagulate.
Colloidal Impurities – Removed by alum and filteration of water
Soluble impurities-
Biological Impurities-
6.1.1 VARIOUS PROCESS THAT ARE INVOLVED IN
TREATMENT OF WATER:
1. Coagulation with chemical addition in slash mixture.
2. Filteration in rapid gravity filter
3. Chlorinisation for removal of organic matter.
4. Clarification in clariflocculator.
The coagulated particles are removed in form of sledge. filteration plant consisting of
rapid gravity filters supplies filtered water for dm plant. Raw water is pumped by means
of pumps located in CW pump house and enters the clariflocculator through a raw water
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inlet channel and flash mixer. Alum, lime and chlorine solution are dosed in raw water
channel and mixed with it. A tap of is taken from the clarified water channel to five rapid
sand filter of capacity(60 m3/hr each). Now it is purified to dm water requirement of all
the 4 units. M?S Geo Miller & Co. Pvt. Ltd. Supplies equipment for this plant
6.1.2 DEMINERALIZING PLANT
Purified water coming from classifier is sent to dm plant through pumps. Impure water
causes sludge and scale formation inside the boiler hence the need of dematerialized
water arises. The water in dm plant undergoes through various steps.
1. ACTIVATED CARBO FILTER (ACF):
Tank in which alternate layers of CO2 and sand are placed. Ac waterfalls from top,
suspend particles (not removed by classifier) are filter. Also the excess of chlorine is
removed from here water goes into SAC tank.
2. STRONG ACID CATION TANK (SAC TANK):
This tank has 2 layers of resins which is used to remove cautions or positive ions viz.
Ca2+
, Mg2+
, Fe2+
, K+.
(R) – H + CaSO4 -----> R- Ca + H2SO4/H2CO3/HCO3/HCL
Resin is a polymer of PVC. It contains polystyrene and polyvinylchloride. From SAC
tank, water is pumped to degassifire.
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6.1.3 DEGASSIFIRE
In it oxygen is removed from the water to avoid corrosion at later stages water falls from
the top and air at high pressure is passed as a jet through it in a partially evacuated
chamber like vessel. This take away the oxygen from water. Now the water is pumped to
WVA tank. It improves pH of the water.
6.1.4 WEAK BASE ANION TANK
In this tank, the negative anions are removed from minerals by the reaction
(R) – OH + H2SO4 -----> H-OH + RSO4
The R SO4 part is filtered through resin layer used. The filtered from above process is free
from trivalent ions and most of the bivalent ions. Bivalent ions left and the monovalent
ions are removed in SBA tank.
6.1.5 POLISHINGING UNIT
It consists of tank which have mixed bed (layers, which have the ability remove positive
as well as negative ions). The water emerging out of this unit is dm water.
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6.1.6 DM WATER QUALITY
pH between 6 to 8
Iron, free CO2 not traceable
Conductivity less than 0.3 micro siemons / cm at 20°c
Total silica less than .020 PPM
Total electrolyte less than 0.1 PPM
After both the anion and cation exchanger get exhausted, anion exchanger is then
treated with NaOH and cation exchanger is then treated with H2SO4
6.1.7 WATER SOFTNER
water softening plant also known as zeolite water softening plant has been provided to
meet bearing cooling water and make up water loss.
6.1.8 ANALYZER DM PLANT
Analyzer is an instrument, which is used for the monitor the situation of water at various
points . analyzer is an instrument because it -
1. Gives an inside picture of the process and avoid shut down of machine.
2. it prevent the change in boiler , tubes , turbine blades and generator.
3. SiO2, Na , dissolved O2 ,NH3 Are monitored when the quantity is exceeding by a
limit.
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THE MONITORING POINTS ARE
1. HPH to economizer - O2
2. at boiler - SiO2 , Cl
3. Condenser to extraction pump
4. Water treatment plant to condenser – (Na , SiO2)
SPECIFICATIONS OF CW PUMPS
Power 1700KW
Rated capacity 16000m3/hr each
Rated speed 497rpm
No load current 81 amp
Full load current 193.7 amp
Direction of rotation Clock wise from top
Voltage 6.6KV
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6.1.9 CW PUMP HOUSE
The cooling water for condenser should be drawn from intake sump through CW pump.
At the entrance of each CW pump, there exists a seal pit from intake sump, traveling
water screens are provided for efficient screening of cooling water and preventing devris
from going into cooling system
The hot water from each unit condenser is connected to seal pit. The CW pipe work is
provided with necessary butterfly valves and rubber expansion joints at require points.
6.1.10 WATER CLARIFIER
It is provide for removing turbidity. Suspended and colloidal solids from raw water by
chemical treatment. All pipe works, storage tanks chemical dosing equipments are
designed to meet the requirements. The raw from chambal river will be taken into the
outdoor CW sumps through CW intake channel. To collect water in this sump will be
pumped to clarification and filteration plants. Through vertical turbine raw water pumps
located in the pump house. The raw water pumps located in the pump house.
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6.2 TURBO-GENERATOR AND EXCITATION SYSTEM
An Turbogenerator is an electromechanical device that converts mechanical
energy to electrical energy, using a rotating magnetic field
6.2.1 THEORY BEHIND THE WORKING OF A TURBOGENERATOR
An Turbogenerator generally includes a rotor that rotates within a stator core to
convert mechanical energy into electrical energy.
A frame-supported stator core provides a high permeability path for magnetic flux
and a rotor assembly positioned to rotate continuously within the stator core so as
to induce electrical current.
The resulting current is carried by high-current conductors through and out from
the power generator, to connectors that provide the current to a plant bus for
power distribution.
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6.2.2 Main Components of Generator
• Stator
– Stator Frame (Fabrication & Machining)
• Core Assembly
– Stator Core, Core Suspension Arrangement
• End Shield
• Stator Winding Assembly
– Stator Winding , Winding Assembly, Connecting Bus bar, Terminal
Bushing
• Rotor
– Rotor Shaft, Rotor Wedges, Rotor Coils, Wound Rotor, Rotor Assembly
• Completing Assembly
– Bearing Assembly, Shaft Seal Assembly, Oil Catchers, Insert Cover etc
• Exciter
• Auxiliary Systems
6.2.3 FUNCTIONS OF EXCITATION SYSTEM
GENERATION OF AIR GAP FLUX TO GET ELECTRICAL OUTPUT.
TO GENERATE SYNCHRONISING TORQUE TO KEEP THE MACHINE IN
SYNCHRONISM.
TO GENERATE REACTIVE POWER (MVAR)
FAST RESPONSE TO SYSTEM DISTURBANCES.
CAPABILITY TO GENERATE FIELD FORCING CONDITION FOR
PROMPT CLEARANCE OF FAULTS.
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6.2.4 BRUSHLESS EXCITATION SYSTEM
CONTACT LESS SYSTEM
ELIMINATES ALL PROBLEM RELATED TO TRANSFER OF POWER
BETWEEN
STATIONARY AND ROTATING ELEMENTS
COMPLETELY ELIMINATES BRUSHGEAR ,
SLIPRINGS, FIELD BREAKER .
ELIMINATES THE HAZARD OF CHANGING
BRUSHES ON LOAD
BRUSH LOSSES ARE ELIMINATED
RELIABILITY IS BETTER
IDEALLY SUITED FOR LARGE SETS
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CHAPTER-7
220KV SWITCH YARD & TRANSFORMER AND
MAINTENANCE WORK
7.1 220KV SWITCH YARD
7.1.1 BUS SCHEME
Main Function Of The Stations Is To Receive The Energy And Transmit It At The
Required Voltage Level With The Facility Of Switching.
At STPS Following Are The Bays:-
1 Bus Coupler - 1
2 Sog -1
3 Sog -2
4 Generator Transformer -1
5 Ratangarh -1
6 Station Transformer -1
7 Bus Sectionalizer
8 Ratangarh - 2
9 Bus Tie
10 Generator Transformer-2
11 Interlinking-1
12 Station Transformer-2
13 Interlinking -2
14 Station Transformer-3
15 Station Transformer-4
16 Station Transformer-5
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7.1.2 Bus System
There Are Mainly Three Buses
1 Main Bus-1
2 Main Bus-2
3 Transfer Bus
Material of bus bar- Tarantull Al conductor with a capacity of 2400 amperes. Bus
coupler-1 can be used as GT breaker for unit 1, 2 and 3. Only one bus coupler can be
used as a GT breaker at a time.
7.1.3 SF6 GAS CIRCUIT BREAKERS:
In this type of breaker quenching of arc is done by SF6 gas. The opening and closing of
the circuit breaker is done by air.
TYPE DESIGNATION:-
E : S F 6 Gas Insulation
L : Generation
F : Out Door Design
SL : Breaker Construction
4 : Code BIL Rated Voltage 4 - 245 / 460 / 1050 kv
1 : No. of chamber
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The high voltage circuit breaker type ELF SL 4-1 comprises 3 breaker poles , a common
control cubicle and a pneumatic unit ( compressed air plant)
A breaker pole consists of :-
- SUPPORT (FRAME) - 40000
- POLE COLUMN - 41309 N
- PNEUMATIC ACTUATOR ( PKA) - 90200
The actuator is operated with compressed air.
A pneumatic unit ( 97200), an air receiver and a unit compressor is installed to supply
the compressed air. the compressed air stored in the air receiver is distributor to the three
actuator via pipe line.
The common control cubicle ( 96000), which is installed separately contains all control
devices and most of the monitoring instrumentation with the exception of the density
monitor 98005 mounted on the middle breaker pole. the pressure switches are installed in
the control cubicle. all three poles columns are filled with insulating gas and
interconnected by means of pipe lines. the gas is monitored by a density monitor 98005 (
temp. compensated pressure monitor )
If all the poles of the circuit breaker do not close simultaneously then the pole
discrepancy relay will operate and trip the breaker. Also at the time of tripping, if all the
breake rs do not trip simultaneously, then again the tripping command through the pole
discrepancy relay will initiate to trip the breaker and annunciation will appear in the sub
station control room and the UCB.
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7.1.4 ISOLATORS:
Isolators are used to make or break the circuit on no load. They should never be operated
on load. The isolators installed in the sub station have a capacity of 1250 amperes. They
are double end break type, motor operated and can be operated from local as well as
remote.
7.2 TRANSFORMERS
7.2.1 CURRENT AND CAPACTIVE VOLTAGE TRANSFORMERS:
These are used for metering and protection. It should always be kept in mind that a CT
should never be open circuited and a PT should never be short-circuited.
7.2.2 LIGHTINING ARRESTOR AND ARC HORNS:
Protection against lighting.
7.2.3 CHANGE OVER SCHEMES (BUS TIE SYSTEM):
When main breaker is in service (on load change over):
1 Ensure Transfer bus is free (check any temporary earthing)
2 Charge the transfer by closing bus coupler isolator and circuit breaker.
3 Put the switches provided on bus coupler on generator control cum desk panel.
4 Charge the transfer bus by closing isolator d of GT.
5 Check the isolator of GT through which it has been already connected to the bus.
6 Close the isolator e,f, & g of tie Bus.
7 By using synchronizing trolley close the circuit breaker b1
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BUS COUPLER TO MAIN BREAKER
o Close the isolator 1 & 3 of GT.
o Close the breaker a 1 of GT
o Close the isolator 5,7 & breaker b 1
o After this work close the isolator 9, 10
o By using synchronizing Troley, close the bus coupler breaker c1
7.2.4 SYNCHRONIZATION OF THE GENERATOR TO THE GRID
(Generator breaker is used)
With The Main Bus:
1. Close the isolator with the bus selection
2. Close the isolator on both sides of the generator breaker.
3. On Generator control desk panel(GCDP)
a. Put the switch NIT in normal position.
b. Put the synchroscope ON.
c. Measure the voltage and speed matching. Conditions will be included by
checking the synchronizing lamp on GCDP and close the generator
breaker.
IMPORTANCE OF THE TRANSFER BUS
Transfer bus is normally free and is used to facilitate repairing job of other breakers by
transferring load on transfer bus
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7.3MAINTENANCE JOBS TO BE DONE ON 220KV SWITCH YARD
7.3.1 Daily Job
Visual checking for any hot spot
Checking of air leakage from the breaker
Checking for any gas leakage from the breaker
Checking of air pressure of breaker
Checking of gas pressure of breaker
Checking of oil leakage form CT and CVT
Checking of oil level from CT and CVT
Checking of lubricating oil level in compressors
Checking healthiness of trip circuit for all breakers.
7.3.2. Monthly Job
Thermo vision scanning of conductor joints and attending to the hot spot on available
opportunity
Breaker operation checking from local and remote
Isolators operation from remote and local.
Measurement of specific gravity and voltage of 220 V D. C> Battery cells.
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7.3.3. Quarterly Job
1) Breakers
1. Tightening of breaker clamps
2. Cleaning of breaker cubicles
3. Checking of oil level of compressors of SF6 breakers.
4. Lubrication of rollers, mechanism shafts, anti pumping pin and c clips.
5. Checking operation of breakers through trip coil 1, trip coil 2, both the coils,
anti pumping operation and pole discrepancy operation
6. Checking of pressure of gas and air pressure of breakers.
2) Isolators
1. Tightening of the jumper clamps
2. Tightening of electrical connections
3. Cleaning of male female connections
4. Checking of fuses and replacement there F.
5. Checking of operation of isolators
3) Current transformers
1. Checking of oil level.
2. Checking of oil and leakage
3. Tightening of jumper clamps
4. Tightening of electrical terminal secondary connection
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4) Lightning Arrestors
1. Tightening of jumper connections
2. Tightening of earthing connections
3. Checking of counter reading
4. Checking of porcelain part
5. Checking of grading current
5) Capacitive Voltage Transformer
1. Checking of oil level and leakage
2. Tightening of HT jumper clamps.
3. Tightening of secondary terminal connections
6) Battery 220 V D. C.
1. Cleaning of battery terminals
2. Tightening of battery terminal connections
3. Recording of specific gravity and voltage of each cell.
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7.3.4 DURING ANNUAL SHUT DOWN OF UNITS
1) Breakers
1. Checking and cleaning of porcelain part of the breaker.
2. Tightening of breaker clamps.
3. Cleaning of breaker cubical
4. Tightening of all the terminal connection
5. Lubrication of I) C and D Roller (II) Locking pins (III) Anti Pumping pins
(IV) Mechanism Shafts
6. Recording of closing and tripping of each phase
7. Recording of insulation resistance value of breaker
8. Checking of annunciator and inter locks.
a. Air pressure low
b. Air pressure very low trip circuit cut off
c. Gas pressure low
d. Gas pressure trip circuit off and other ann. of breaker
9. Checking of tripping through
a. Trip Coil I
b. Trip Coil II
c. Through both the trip coils
d. Anti Pumping operation
e. Pole Discrepancy operation
10. Measurement of resistance of trip cells and closing coils
11. Checking of air leakage and its stoppage
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12. Checking the gas leakage
13. Replacing the oil of compressors
14. Checking of auto operation of compressors
15. Complete maintenance of compressors
16. Checking of closing/tripping of breaker from local remote
2) Isolators
1. Cleaning of male female connections
2. Tightening of all the jumper clamps
3. Lubrication of control rotary post insulator with grease
4. Checking of proper operation of the isolator
5. Tightening of all the nuts and bolts
6. Cleaning the motor cubical
7. Tightening of all the terminal connections
8. Greasing the gear box of motor
9. Checking of all the fuses
10. Checking of operation of isolator from local/remote
3) Current Transformers
1. Checking / cleaning of porcelain part of CT
2. Checking of oil and level and stopping it if low
3. Checking of oil leakage and its stoppage
4. Checking of N2 pressure and maintaining it at 0.2 kg/cm2
5. Tightening of earthing connection
6. Checking of BDV value of CT oil
7. Tightening of all the secondary terminal connections
8. Cleaning of marshalling box and tightening of terminal connections
9. Recording of IR values of primary and secondary side of CT
10. Tightening of bushing clamps.
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4) Capacitive Voltage Transformers
1. Checking of oil level and topping thereof
2. Checking of N2 pressure and maintaining it at 0.2 kg/cm2
3. tightening of jumper clamps.
4. Tightening of secondary connection
5. Recording of IR values of primary and secondary side
6. BD value of oil
5) Lightning Arrestors
1. Cleaning of porcelain part and checking
2. Tightening of earthing connection
3. Tightening of jumper connection
4. Recording of IR values
5. Checking of counter readings
6. Checking of grading current
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CHAPTER-8
DC SYSYTEM & POWER LINE CARRIER
COMMUNICATION
8.1 DC SYSTEM
8.1.1 BATTERIES
Main Building
• Wet cell battery bank
o 125 V Battery Bank – 1
o 125 V Battery Bank – 2
o 125 V Battery Bank – 3
o 125 V Battery Bank – 4
o 220 V Battery Bank – 1
o 220 V Battery Bank – 2
• Dry cell battery
o Battery Bank
8.1.2 SWITCHYARD BUILDING BATTERY BANK
220 V Battery Bank – 1
220 V Battery Bank – 2
48 V Battery Bank – 1
48 V Battery Bank – 2
8.1.3 BATTERY ROOM
Battery room should be well ventilated, clean, dry and temperature moderate
(Damping is dangerous due to possibility of earth leakage from the battery)
Smoking is prohibited
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Battery get best result at the room temperature between 20 – 35o C
8.1.4 ELECTROLYTE
It is a mixture of Acid and Pure Water (Distilled) with proper portion.
General value of proportion is 85 % water and 15 % acid.
Gravity to be maintained 1.200 + 0.005 in al the cells.
CAUTION
Batteries and Battery Room should be clean, dry and well ventilated.
Never allow a flame, cigarette near the batteries.
Wear old clothes or terylene when working with acid or electrolyte (Terylene is
resistant to dilute acid).
Never add water to acid. It will spurt dangerously
8.1.5 TEMPERATURE CORRECTION
The specific gravity of the electrolyte works with temperatire. Any reading
observed on the hydrometer should therefore be corredted to 270o C as all the
specific gravity values indicated by use are at 27o C
For every 1o C above 27o C add 0.007 to the specific gravity as read on
hydrometer
8.1.6 NORMAL OPERATION OF BATTERIES
Keep the battery on trickle charge continuously (25 hrs. each day) except where it
is on discharge or on Boost charge.
The trickle charge current shown on milli ammeter should be so adjusted that the
battery be kept fully charges without being over charged.
The trickle charging current should be so appropriate that it should neither be too
much trickle charge not too little trickle charge.
The value above 2.3 and below 2.25 volts per cell during routine checking it
found means adjustment of trickle charging current is required.
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8.2 POWER LINE CARRIER COMMUNICATION
8.2.1 EARTH SHIELDING
It is a mesh of wire upon the tower. Its main purpose is to protect the substation
equipment from direct lightning strokes. Metallic body of each equipment is properly
earthed. The earthing resistance of any switch yard is about 0.2 ohm. Before the building
up of the sub station earthing material of G. I. wire is buried in the ground whose depth
depends upon the moisture content of ground. Earthing electrodes are provided at various
points. This increases the number of parallel provided at various points. This increases
the number of parallel paths and hence resistance of earth decreases.
This is a technique in which power lines are used as communication lines by which we
can make contact with other substation
The range of frequency used for communication is 300 KHz to 500 kHz.
8.2.2 WORKING
The voice frequency if converted into electrical signal. These signals are super imposed
on a carrier frequency and transmitted on the line through a coupling capacitor. At the
receiving end wave trap does not allow the modulated signal to enter the power circuit
where as the coupling capacitor provides a low resistance path to this signal. This signal
is then given to the line matching unit. In the LMU this frequency is matched and after
wards filtration of signal is done. The signal is demodulated and again converted into the
voice signal, which is available at phone receiver.
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RESULT AND CONCLUSION
The Summer Training completed in Dholpur Combined Cycle Power Project
(DCCPP) during the period 25th
May 09 to 17th
July 09 is successful in all respects. There
I studied Gas Turbine, Steam Turbine, Boilers and all equipments that are use for
generating the electricity.
On doing Summer Training there I came to know that DCCPP project is under the
RVUNL (Rajasthan Rajya Vidhyut Utpadan Nigam Ltd.) and It’s capacity is 330MW.
It has been a wonderful experience for me for working in DCCPP as a Trainee and
if given chance I would like to be a part of this Organisation.
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BIBLIOGRAPHY
rvunl.com
google.co.in
wikipedia.org
Own Experience
top related