Practical Training Report
ADANI POWER LIMITED
Submitted in partial fulfillment for the award of the degree of
BACHELOR OF TECHNOLOGY
(13 May 2013- 13 June 2013)
Submitted by :-
B.Tech VIIth sem
SIR PADAMPAT SINGHANIA UNIVERSITY
TO WHOM IT MAY CONCERN
I hereby certify that NIPRANCH SHAH roll no. 10ME001073 of Sir
Padampat Singhania University undergone thirty days industrial
training from 13th
May 2013 to 13th
June 2013 at our organization to
fulfill the requirement for the award of degree of B.TECH Mechanical
Engineering. During his tenure with us we found him sincere and hard
We wish him a great success in the future.
Signature of student
A student gets theoretical knowledge from classroom and gets practical
knowledge from industrial training. When these two aspects of theoretical
knowledge and practical experience together then a student is full equipped to
secure his best.
In conducting the project study in an industry, students get exposed and
have knowledge of real situation in the work field and gains experience from
them. The object of the summer training cum project is to provide an opportunity
to experience the practical aspect of Technology in any organization. It provides
a chance to get the feel of the organization and its function.
The fact that thermal energy is the major source of power generation
itself shows the importance of thermal power generation in India – more than 60
percent of electric power is produced by steam plant in India.
In steam power plants, the heat of combustion of fossil fuels is utilized
by the boilers to raise steam at high pressure and temperature. The steam so
produced is used in driving the steam turbine coupled to generators and thus in
generating ELECTRICAL ENERGY
INTRODUCTION TO THE COMPANY
ABOUT THE COMPANY
Adani Power Limited is the power business arm of Indian business conglomerate
Adani Group with head office at Ahmedabad, Gujarat. The company is India's
largest thermal private power producer with capacity of 5280 MW and also it is
the largest solar power producer of India with capacity 40MW.
The company currently operates five supercritical boilers of 660MW each (as per
March 2012) at Mundra Gujrat & One 660MW out of 05 units at Tirora,
Maharashtra. It also operates a mega solar plant of 40MW at Surendra nagar,
Gujrat. It is India's first company to achieve the supercritical technology. The
plant is the only thermal power plant in india to be certified by UN under CDM.
The company is currently implementing 16500 MW at different stages of
construction. Its mission is to achieve 20000 MW by 2020. The company
currently produces electricity using only coal. 100MW of solar power station is
also under advanced stage of implementation at Surendranagar in Gujarat out of
which 40MW is already commissioned. The company has gone to long term
PPAs of about 7200MW of its 9280MW with government of Gujarat,
Maharashtra, Haryana and Rajasthan
The company was changed to Adani Power Private Limited. The RoC issued a
fresh certificate of incorporation on 3 June 2002. The Company was, thereafter,
converted into a public limited company on 12 April 2007 and the name of the
Company was changed to Adani Power Limited. Further, upon ceasing to be a
private limited company, the word private was deleted through a special
resolution at the EGM of the Company held on 28 March 2007. The fresh
certificate of incorporation consequent to change of the name was granted by the
RoC to the Company on 12 April 2007.
Adani power was started as a power trading company 1996. It started generation
in July 2009 by implementation of its first 330MW of 4620mw at Mundra. The
Mundra super mega project is the largest coal based power project of India and
fifth largest in the world. The company commissioned another three 330 MW by
November 2010 and country's 1st supercritical unit of 660 MW on 22 December
2010, making its capacity 1980 MW. 0n 6 June 2011 it synchronized its second
unit of 660 MW bringing the total generating capacity to 2640 MW and on 2
October 2011, it synchronized its third super critical unit with national grid .With
this,Adani power has become largest thermal power generating company in the
private sector and the Mundra plant has become India's Largest Power plant with
capacity 3300MW. In February 2012, it commissioned the last unit of Mundra
Project to take its capacity to 4620MW which makes the Mundra TPP to be the
largest privately held Thermal power plant of World and fifth largest on an overall
basis(As per March,2012).
The company currently operates 4620 MW coal based Mundra Thermal Power
Station at Mundra, Gujarat. It operates first power transmission project of 400KV
Double Circuit Transmission System from the Mundra plant to Dehgam (430
km). The company operates India's first supercritical unit of 660MW. It also
implemented country's only private 1000 km HVDC transmission line for
efficient transmission of power to Haryana. The company produces 40MW of
solar power in Gujrat showing its interest in renewable energy.
The company is currently implementing thermal projects of 3300MW
(5X660MW) at Tiroda, Maharastra at Tirora one unit of 660 MW have been
generating Power since Mid of 2012 & another is going to commissioned in the
end of 2012 and 1320MW (2X660MW) at Kawai, Rajsthan, and a 100 MW solar
project at Surendranagar,Gujrat(40MW commissioned).
As of January 2011, the company has 16500MW under implementation and
planning stage. A few of them are 3300MW coal based TPP at Bhadreswar in
Gujarat, 2640 MW TPP at Dahej in Gujarat, 1320 MW TPP at Chhindwara in
Madhya Pradesh, 2000 MW TPP at Anugul in Orissa and 2000MW gas based
power project at Mundra in Gujarat. The company is also bidding for 1000 MW
of lignite coal based power plant at Kosovo showing its international projects.
1. INTRODUCTION TO THE POWER PLANT
Electricity is the only form of energy which is easy to produce, easy to transport,
easy to use and easy to control. So, it is mostly the terminal of energy for
transmission and distribution. Electricity consumption per capita is the index of
the living standard of people of place or country.
Electricity Demand and Supply in India: India is facing energy shortages of 11%
of demand and even higher peak shortages of 14%Demand-supply gap is more
acute in Western region (where 70% of the Project’s power will be supplied) with
energy deficit at 16% and peak deficit at 21% Capacity additions of 160,000
MW required in the next 10 years to meet India’s power demand. New capacity
need to be added using a combination of coal, hydro, gas, nuclear and wind
Types of Power Plants: Electricity in bulk quantities is produced in power plants,
which can be of the following types:
India’s Installed Capacity (132,329 MW)
Coal & lignite Gas Hydro Nuclear Other
2. LOCATIONAL DETAILS OF MUDRA
Latitude : 22º48’35”N
Longitude : 69º32’53”E
Nearest Village : Tunda, Taluka Mundra, Dist Kutch, Gujarat State.
Mean Sea Level : 5.1 m
Total area : 294 Ha
State Highway : SH6 - 3.4 KM
National Highway : NH 8A extension - 5.7 km
Nearest port : Mundra Port – 17.23 km
Bhuj : 52 KM
Kandla : 64 KM
Adani Pvt. Port : 25 KM
3.OVERVIEW OF POWER PROJECT at MUNDRA
Mundra Thermal Power Project
Power Generation Capacity
Adani Group’s foray into power sector –
The Group’s foray into power sector is natural extension for Adani Group, which
has emerged as India’s largest coal importer and second largest power entity in
Adani Power Ltd (APL) is setting up a 4620 MW power project at Mundra based
on imported coal. The execution will be done in the following stages;
2*330 Phase I (sub critical)
2*330 Phase II (sub critical)
3*660 Phase III (super critical)
2*660 Phase IV (super critical)
5.DIAGRAM OF A TYPICAL COAL-FIRED THERMAL
1. Cooling tower 10. Steam Control valve 19. Superheater
2. Cooling water pump 11. High pressure steam turbine 20. Forced draught (draft) fan
3. transmission line (3-phase) 12. Deaerator 21. Reheater
4. Step-up transformer (3-phase) 13. Feed water heater 22. Combustion air intake
5. Electrical generator (3-phase) 14. Coal conveyor 23. Economiser
6. Low pressure steam turbine 15. Coal hopper 24. Air preheater
7. Condensate pump 16. Coal pulveriser 25. Precipitator
8. Surface condenser 17. Boiler steam drum 26. Induced draught (draft) fan
9. Intermediate pressure steam turbine 18. Bottom ash hopper 27. Flue gas stack
Main parts of the plant are
1. Coal conveyor………………………………………………………….13
5. Air preheater…………………………………………………………….32
9. Cooling towers…………………………………………………………..43
10. Electrostatic precipitator…………………………………………..…...45
11. Smoke stack……………………………………………………………45
1. COAL CONVEYOR-
Coal conveyor is a belt type of arrangement. With this coal is transported from
coal storage place in power plant to the place near by boiler. Adani Power Ltd.
have the longest conveyor in India of 7KM long which convey the coal from the
port to the plant.
Phase I & Phase II
Capacity : 5.50 T/ Hr / 6.6 T/Hr
Phase III & Phase IV
Capacity : 10-104 t/h
The coal which is brought near by boiler has to put in boiler furnace for
combustion. This stoker is a mechanical device for feeding coal to a furnace. It
is also called feeder or hopper.
3. PULVERIZER OR COAL MILL-
The coal is put in the boiler after pulverization. For this pulverizer is used. A
pulverizer is a device for grinding coal for combustion in a furnace in a power
Phase I & II : 5/6 mills per unit
Phase III & IV : 6 mills per unit
COAL MILL Phase I / Phase II
No. of coal mills : 5 Nos. / 6 Nos.
Maximum capacity : 38.7 TPH / 43.7 TPH
Mill speed : 26.4 rpm
No. of coal Bunkers : 5 Nos. / 6 Nos
Mill type : Medium speed vertical grinder roller
Make : Beijing Power Equipment Group
Coal fineness : 75 µ
Capacity of Bunkers : 400 MT Each
Capacity of coal feeder : 50 TPH
Outlet PA / Coal temp. : 85° C
Coal Mill Phase III & IV
No of Coal Mills : 6 nos.
Mill Type : Medium Speed Bowl Mill
Maximum Capacity : 86 t/h
Mill Motor Rated Power : 950KW
Gear Box : Spiral Bevel Gear & Planetary
Mill Speed : 27.7 r/min
No. of Coal Burners : 24
Type of Construction : Tangential type tilting burner
Coal Feeder Type : Variable Frequency
No. of Coal Bunkers : 6nos.
Coal Bunker Capacity : 979 m^3.
Outlet PA / Coal temp. : 85° C
Working Of Coal Mill-
1. Anthracite coal from the coal wagons is transported to the coal handling plant.
2. Here coal is crushed in crushers and reduced to 1 inch size (approx.).
3. This crushed coal is transported to the coal bunkers with the help of coal
4. With the help of coal feeders coal from bunkers is made to fall in Coal mill.
5. Coal is grounded to powdery form in bowl mill. This finely grounded coal is
known as pulverized coal. Bowl mill consists of a round metallic table and three
rollers. Rotating table is made to rotate with the help of a motor. There are three
large rollers which are at a spacing of 120°.When there is no coal these rollers
does not rotate but when coal is fed to the table it packs between the table and the
roller and this forces the rollers to rotate. Coal is crushed by the crushing action
between table and rollers.
6. This pulverized coal is taken to the burner in coal pipes with the help of hot
and cold air mixture from primary air (PA) fan.
Now that pulverized coal is put in boiler furnace. Boiler is an enclosed vessel
in which water is heated and circulated until the water is turned in to steam at
he required pressure.Coal is burned inside the combustion chamber of boiler.
The products of combustion are nothing but gases. These gases which are at
high temperature vaporize the water inside the boiler to steam. Some times
this steam is further heated in a super heater as higher the steam pressure and
temperature the greater efficiency the engine will have in converting the heat
in steam in to mechanical work. This steam at high pressure and temperature
is used directly as a heating medium, or as the working fluid in a prime mover
to convert thermal energy to mechanical work, which in turn may be converted
to electrical energy. Although other fluids are sometimes used for these
purposes, water is by far the most common because of its economy and
suitable thermodynamic characteristics.
There are two types of boiler in the power plant subcritical & supercritical
330MW unit have subcritical boiler and 660MW unit have supercritical
• The supercritical technology is the thermodynamic state where there is no
clear distinction between the Water and Steam phase in the Rankine Cycle
• Water reaches to steam state at a critical pressure above 22.1 MPa at 374°C.
• The “efficiency “of the thermodynamic process is the heat energy fed into
the Rankine cycle is converted into electrical energy.
• Heat energy input to the Rankine cycle is kept constant, the output can be
increased by selecting high pressures and high temperatures.
• The key components are supercritical once through boiler and high pressure
& high temperature steam turbine.
Difference between Sub-Critical and Super-Critical Boilers
SUB-CRITICAL BOILERS SUPER-CRITICAL BOILERS
Operating pressure is below 225.5 bar. Operating pressure is above 225.5 bar.
circulation by pump assisted or natural
Lower load start-up circulation: below
35% NR load.
Power plant efficiency is around 35% Power plant efficiency is around 39%
Pressure : 169 bar
SH Temp : 538°C
RH Temp : 538°C
Pressure : 254 bar
SH Temp : 571°C
RH Temp : 571°C
Base Additional cost to manufacturing and
erection of furnace wall.
Vertical water walls. Spiral wounded tilted water walls ensures:
Heat distribution on each wall is more
uniform than vertical water walls. Avoid
higher thermal stresses in water- walls by
reducing the fluid temperature difference
in adjacent tubes.
Steam Drum: For separation of Water and
Steam Drum is not used.
Water Walls /Evaporator –
The furnace circuitry consists of a lower section with optimized, vertical rifled
tubes that extend up to transition headers located at an elevation below the furnace
nose. The transition headers are interconnected to provide pressure equalization
to minimize flow unbalances and provide circuit flow stability. Above the
transition header location, vertical smooth bore tubes extend up to the furnace
roof, and also form the furnace exit screen and part of the vestibule side walls.
The tube panels that form the furnace enclosure are of Monowall type
construction. Risers pipes extend from the furnace enclosure upper headers and
are routed to a collection manifold from which the flow is directed to a final
evaporator zone that forms the furnace nose, vestibule floor and approximately
half of the vestibule sidewalls. The furnace enclosure tube size and spacing were
selected to provide a low mass flux (nominally 1000 kg/m2-s at full load) to
provide a “natural circulation” flow characteristic (as will be described in a
subsequent section) to accommodate radial heat absorption variations around the
perimeter of the furnace. Tube sizes and spacing, membrane fin sizes, and
materials are all selected to provide for base load service as well as the defined
cyclic operation of the plant.
The final evaporator zone that forms the furnace nose, vestibule floor, and part of
the vestibule sidewalls is provided to act as a buffer circuit to minimize tube
temperature differentials between the furnace evaporator walls and the adjacent
HRA enclosure superheater panels during start-up and transient conditions. The
interface between evaporator and superheater tubes is positioned near the center
of the vestibule to avoid structural discontinuities such as enclosure corners where
stress concentrations are the greatest. From the vestibule enclosure, steam is
directed to four in-line steam/water separators connected in parallel, which are
part of the start-up system, which is described below.
Subcritical boilers are consist of drum arrangement and supercritical
boilers are consist of separator. The separator are once through
DRUM vs ONCE THROUGH
Pressure Sub critical Sub & super critical
Steam separation Drum Separator(low loads)
Types Natural / assisted Sulzer / benson
Burner panel Straight tube Spiral tube / straight(MHI)
Load change Base Faster
Cold start 4-5 Hours 2 Hours
Hot start 1-2 Hours 0.5 Hours
An economizer is a heat exchanger which raises the temperature of the
feedwater leaving the highest pressure feed water heater to about the saturation
temperature corresponding to the boiler pressure. This is done by the hot flue
gases exiting the last superheater or reheater at a temperature varying from
370`C to 540`C. The throwing away of such high temperature gases involved a
great deal of energy loss. By utilizing these gases in heating feedwater, higher
efficiency and better economy were achieved.
The flue gases coming out of
the boiler carry lot of heat. An
economiser extracts a part of
this heat from the flue gases and
uses it for heating the feed water
before it enters into the steam
drum. The use of economiser
results in saving fuel
consumption and higher boiler
efficiency but needs extra
investment. In an economizer, a
large number of small diameter
thin walled tubes are placed
between two headers. Feed water enters the tubes through the other. The flue
gases flow outside the tubes.
The superheater is a heat exchanger in which heat is transferred to the saturated
steam to increase its temperature. It raises the overall cycle efficiency. In addition
it reduces the moisture content in the last stages of the turbine and thus increases
the turbine internal efficiency. In modern utility high pressure boilers, more than
40% of the total heat absorbed in the generation of steam takes place in the
superheaters. So, large surface area is required to be provided for superheating of
Superheaters are commonly classified as:
Primary Superheater or the Low Temperature Superheater (LTSH):
Platen or pendent panel Superheater:
Ceiling Superheater: A panel of small bore tubes interconnecting long header
at both ends, forms the roof of the furnace and the second pass of flue gas path.
From here the steam flows through different stages of superheating.
Primary Superheater or the Low Temperature Superheater
(LTSH): A panel of small bore tubes formed in “U” shaped coils is connected
to long headers on either ends and located horizontally in second Pass of the flue
gas path above the economizer. Superheated steam from Ceiling Superheater
enters at inlet and gets heated further, raising the steam temperature. It is located
in the low temperature region of flue gas path. The steam just gets superheated
and the temperature range to which the steam is heated is very low compared to
the final outlet steam temperature and hence called Low Temperature
Platen or pendent panel Superheater: Steam from Primary Superheater
enters the Platen Superheater. The Platen Superheater is located just above the
combustion zone at the top of the furnace. Mainly it receives radiant heat from
the furnace and the steam is further superheated. They are hanging panels
arranged in rows across the width of the furnace. Each panel is connected with its
own small inlet and outlet headers, which are in turn is connected to the big and
long common headers, on both inlet and outlet sides.
Convection Superheater: From Platen Superheater the steam enters the next
stage of superheating, which is called Convection Superheater. Convection
Superheater is located away from radiant zone of the furnace and the heat transfer
takes place by convection process, when the mass of flue gases pass through and
across the convection Superheater coils. The steam gets its final heat addition
while flowing through the final Superheater stage and flows out through main
steam pipes, for the end use.
Some of the heat of superheated steam is used to rotate the turbine where it loses
some of its energy. Reheater is also steam boiler component in which heat is
added to this intermediate-pressure steam, which has given up some of its energy
in expansion through the high-pressure turbine. The steam after reheating is used
to rotate the second steam turbine where the heat is converted to mechanical
energy. This mechanical energy is used to run the alternator, which is coupled to
turbine , there by generating electrical energy.
Boiler Technical data:-
I. Manufacturer : Harbine boiler company
II. Model : HG 2115/25.4-HM15
III. Type : Supercritical once through, primary
inter-mediate reheating, single furnace,
II type suspended structure.
IV. Type of firing : Wall mounted tangential firing
V. Water volume capacity : Economizer system – 65 m3
Water wall system – 70 m3
Start up system – 22 m3
Super heater – 227 m3
Re-heater – 435 m3
DESIGN SPECIFICATION OF THE BOILER
No. Item Specification Unit
1 Model HG2115/25.4 – HM15
2 Mode Once-through boiler with
3 Superheater steam flow 2115.5 t/h
4 Superheater outlet pressure 25.4 Mpa
5 Superheater outlet temperature 571 °C
6 Reheated steam flow 1714.9 t/h
7 Reheater inlet pressure 4.794 Mpa
8 Reheater outlet pressure 4.604 Mpa
9 Reheater inlet temperature 328.6 °C
10 Reheater outlet temperature 569 °C
11 Feedwater pressure 28.87 Mpa(g)
12 Feedwater temperature 292.6 °C
13 Separator’s steam temperature 421 °C
14 Air preheater’s outlet air temperature 153.3 °C
15 Uncorrected after 147.2 °C
16 Calculating thermal efficiency of boiler 92.62% (BMCR)
17 Guarantee thermal efficiency of boiler 92.17% (TRL)
18 Pulverizing type Cold primary fan positive pressure
direct blowing system
19 Burner type Wall – mounted tangential circle
combustion, dry ash extraction
20 Draft type Balanced ventilation
21 Design fuel Indonesian coal
22 Check fuel Indonesian coal
23 Coal-fired quantity of the boiler 338 t/h
24 Check fuel 300 t/h
25 Fuel oil startup and ignition LDO and HDO
26 Superheated steam temperature adjustment Ratio of coal and water, secondary
Furnace dimension (width×height×height×depth)= 23567×17012×616 mm43
Horizontal pass depth : 5322 mm
Back pass front duct depth : 8618 mm
Break pass back duct depth : 9098 mm
Water wall lower header elevation : 7000 mm
Large amount of air is required for combustion of fuel. The gaseous combustion
products in huge quantity have also to be removed continuously from the furnace.
To produce the required flow of air or combustion gas, a pressure differential is
needed. The term “draught” or “draft” is used to define the static pressure in the
furnace, in the various ducts, and the stack.
The function of the draught system is basically two folds:
To supply to the furnace the required quantity of air for complete of fuel.
To remove the gaseous products of combustion from the furnace and throw
these through chimney or stack to the atmosphere.
There are two ways of producing draught:
Natural Draught: The natural draught is produced by a chimney or a stack. It is
caused by the density difference between the atmospheric air and the hot gas in
Mechanical Draught: Mechanical draught is produced by fans.
Induced and Forced Draught Fans:
Big fans may be used for sucking and throwing out the flue gas through the
chimney, thereby creating adequate draught inside the furnace. Such Fans are
termed as Induced Draught Fans. Forced draught Fans may also be deployed for
supply of required quantity of combustion air and maintaining a positive draught
inside the furnace. The flue gas will be pushed out the stack with the draught
pressure available in the furnace.
Forced Draught Fan:
Air drawn from atmosphere is forced into the furnace, at a pressure higher than
the outside atmosphere, by big centrifugal fan or fans to create turbulence and to
provide adequate Oxygen for combustion. Hence the system is known by the
name Forced draught system and the fan, used to push through combustion air
under pressure, is called Forced Draught Fan. F D fan is normally located at the
front or sideways of the furnace.
Induced Draught Fan
Instead of drawing atmospheric air and pushing through furnace, a centrifugal fan
can be deployed to draw out the air from the furnace and throw out through the
chimney, thereby creating negative pressure in the combustion zone and maintain
the negative draught through out the furnace. The system is called Induced
Draught system and the fan deployed for this purpose is known as Induced
In the Induced Draught system, the fan is fitted at back end of the furnace or near
the base of the chimney. Due to the negative pressure created inside the furnace,
by the action of the fan, flue gas will not come out of combustion space i.e.
Furnace. The entry of air to Boiler is regulated through air registers and dampers.
For similar capacity boilers, the size of an induced draught fan will be more than
the size of the forced draught fan required for a forced draught system. This is
because the products of combustion is always much higher in volume than the
volume of combustion air handled by the forced draught fan. Further the flue gas
is hotter and the density is less. Hence the volume is much more. According to
Charles Law, when a gas is heated the volume will proportionately increase at
constant pressure, with the raise in temperature. According to Boyles Law, if
pressure inside a vessel is increased, the volume will proportionately decrease
and the vice-versa is also true (P ∝ 1/V).
Primary air fan
These are the large high pressure fans which supply the air needed to dry and
transport coal either directly from the coal mills to the furnace or to the
intermediate bunker. These fans may be located before or after the milling
equipment. The most common applications are cold primary air fans, hot primary
The coal primary air fan is located before air heater and draws air from the atm.
And supplies the energy required to force air through air heaters, ducts, mills and
fuel piping. With a cold air system like this the FD fan may be made smaller as
PA fan supply part of combustion air.
For primary air fans boosts the air pressure from air heaters for drying and
transporting coal from pulverisers in these systems the total air has to be handled
by FD fans and each mill will be provided with a primary air fan at the mill inlet
side the primary fan in these case has to handle hot air probably with some amount
of fly ash carried from the air pre-heater.
Technical data :-
Description Unit FD PA ID
Fan Model Axial Fan Axial Fan Axial Fan
Rated Power of Motor kW 2000 3150 4500
Rotational Speed of Fan r/min 990 1490 990
Air preheater are in generally divided into following two types:
In Recuperative APH, heat is directly transferred from the hot gases to the air
across the heat exchanging surface. They are commonly tubular, although some
plate types are still in use. Tubular units are essentially counter-flow shell-and-
tube heat exchangers in which the hot gases flow inside the vertical straight tubes
and air flows outside. Baffles are provided to maximize air contact with the hot
Regenerative APH are also known as storage type heat exchangers, have an
energy storage medium, called the matrix, which is alternately exposed to the hot
and cold fluids. When the hot flue gases flow through the matrix in the first half
of the cycle, the matrix is heated and the gas is cooled. In the next half of the
Volume flow of fan inlet m^3/s 230.1 112.9 538.4
Temperature of fan inlet ˚C 47.8 47.8 137
Fan total pressure Pa 3871 12671 3989
Total efficiency % 87 88 85.5
External Diameter of
mm 2880 2100 3349
Diameter of Impeller mm 1600 1400 1884
Blade No. of Each Grade Nos. 26 22 18
cycle when air flows through the matrix, air gets heated and the matrix is cooled.
The cycle repeats itself.
A steam generating boiler requires that the boiler feed water should be devoid of
air and other dissolved gases, particularly corrosive ones, in order to
avoid corrosion of the metal.
Generally, power stations use a Deaerator to provide for the removal of air and
other dissolved gases from the boiler feed water. A deaerator typically includes a
vertical, domed deaeration section mounted on top of a horizontal cylindrical
vessel which serves as the deaerated boiler feed water storage tank.
Turbine is a machine in which a shaft is rotated steadily by impact
or reaction of current or stream of working substance (steam, air, water, gases
etc) upon blades of a wheel. It converts the potential or kinetic energy of the
working substance into mechanical power by virtue of dynamic action of working
substance. When the working substance is steam it is called the steam turbine.
PRINCIPAL OF OPERATION OF STEAM TURBINE:-
Working of the steam turbine depends wholly upon the dynamic action of Steam.
The steam is caused to fall in pressure in a passage of nozzle: doe to this fall in
pressure a certain amount of heat energy is converted into mechanical kinetic
energy and the steam is set moving with a greater velocity. The rapidly moving
particles of steam, enter the moving part of the turbine and here suffer a change
in direction of motion which gives rose to change of momentum and therefore to
a force. This constitutes the driving force of the machine. The processor of
expansion and direction changing may occur once or a number of times in
succession and may be carried out with difference of detail. The passage of steam
through moving part of the commonly called the blade, may take place in such a
manner that the pressure at the outlet side of the blade is equal to that at the inlet
inside.Such a turbine is broadly termed as impulse turbine.On the other hand the
pressure of the steam at outlet from the moving blade may be less than that at the
inlet side of the blades; the drop in pressure suffered by the steam during its flow
through the moving causes a further generation of kinetic energy within the
blades and adds to the propelling force which is applied to the turbine rotor.Such
a turbine is broadly termed as impulse reaction turbine.
The majority of the steam turbine have, therefore two important
elements, or Sets of such elements.These are the nozzle in which the system
expands from high pressure end a state of comparative rest to a lower pressure
end a status of comparatively rapid motion.
The blade or deflector, in which the steam particles changes its
directions and hence its momentum changes . The blades are attach to the rotating
elements are attached to the stationary part of the turbine which is usually termed
the stator, casing or cylinder.
Although the fundamental principles on which all steam turbine
operate the same, yet the methods where by these principles carried into effect
very end as a result, certain types of turbine have come into existence.
1. Simple impulse steam turbine.
2. The pressure compounded impulse turbine.
3. Simple velocity compounded impulse turbine.
4. Pressure-velocity compounded turbine.
5. Pure reaction turbine.
6. Impulse reaction turbine.
Description of Steam Turbines:-
The HP casing is a barrel type casing without axial joint. Because of its rotation
symmetry the barrel type casing remain constant in shape and leak proof during
quick change in temperature. The inner casing too is cylinder in shape as
horizontal joint flange are relieved by higher pressure arising outside and this can
kept small. Due to this reason barrel type casing are especially suitable for quick
start up and loading.The HP turbine consists of 25 reaction stages. The moving
and stationary blades are inserted into appropriately shapes into inner casing and
the shaft to reduce leakage losses at blade tips.
The IP part of turbine is of double flow construction. The casing of IP turbine is
split horizontally and is of double shell construction. The double flow inner
casing is supported kinematically in the outer casing. The steam from HP turbine
after reheating enters the inner casing from above and below through two inlet
nozzles. The centre flows compensates the axial thrust and prevent steam inlet
temperature affecting brackets, bearing etc. The arrangements of inner casing
confines high steam inlet condition to admission branch of casing, while the joints
of outer casing is subjected only to lower pressure and temperature at the exhaust
of inner casing. The pressure in outer casing relieves the joint of inner casing so
that this joint is to be sealed only against resulting differential pressure.
The IP turbine consists of 20 reaction stages per flow. The moving and stationary
blades are inserted in appropriately shaped grooves in shaft and inner casing.
The casing of double flow type LP turbine is of three shell design. The shells are
axially split and have rigidly welded construction. The outer casing consist of the
front and rear walls , the lateral longitudinal support bearing and upper part.
The outer casing is supported by the ends of longitudinal beams on the base plates
of foundation. The double flow inner casing consist of outer shell and inner shell.
The inner shell is attached to outer shell with provision of free thermal movement.
Steam admitted to LP turbine from IP turbine flows into the inner casing from
both sides through steam inlet nozzles.
Engineering Design Aspects
Steam and heat cycle
Dongfang Steam Turbine
Impulse type, tandem compound three
cylinders, four flow exhaust, single
reheat, condensing turbine
TMCR Output 660 MW
BMCR Output 694 MW
HP turbine 8 Stages, 2 Stop valves, 4 control valves
IP turbine 6 Stages, 2 Stop valves, 2 control valves
LP turbine Double flow 2x7 Stages
HP heaters 3
LP heaters 4
No of Extractions 8
No of Journal bearings 6
STEAM FLOW DIAGRAM OF TURBINES AND HEATERS
LOSSES IN STEAM TURBINE
• Friction losses
• Leakage losses
• Windage loss( More in Rotors having Discs)
• Exit Velocity loss
• Incidence and Exit loss
• Secondary loss
• Loss due to wetness
• Loss at theBearings(appx 0.3% of total output)
• Off design losses
MAIN LOSSES IN TURBINE
It is more in Impulse turbines than Reaction Turbines,because impulse turbines
uses high velocity of steam and further the flow in the moving blades of the
Reaction turbines is accelerating which leads to better and smooth flow(Turbulent
flow gets converted to Laminar flow)
It is more in Reaction turbines than Impulse turbines because there is Pressure
difference across the moving stage of reaction turbines which leads to the
Leakages. In Impulse turbine such condition is not there.
• Leakage loss predominates over friction losses in the High Pressure end of
• Friction Losses predominates over the Leakage's Loss in the Low Pressure
end of the Turbine.
• It is observed that the Efficiency of The IP Turbine is the maximum
followed by The HP and LP Turbine.
Features of 660 MW Mundra Steam Turbine
Combined HP & IP Section
Shorter Turbine Length – More Efficient
Reduced No. of Bearings
Reduced No. of Packing segments
Opposite flow in HP & IP Turbines makes thrust force balanced
Casings upper & lower halves are nearly symmetrical
Steam after rotating steam turbine comes to condenser. Condenser refers here
to the shell and tube heat exchanger (or surface condenser) installed at the
outlet of every steam turbine in Thermal power stations of utility companies
generally. These condensers are heat exchangers which convert steam from its
gaseous to its liquid state, also known as phase transition. In so doing, the
latent heat of steam is given out inside the condenser. Where water is in short
supply an air cooled condenser is often used. An air cooled condenser is
however significantly more expensive and cannot achieve as low a steam
turbine backpressure (and therefore less efficient) as a surface condenser.
The purpose is to condense the outlet (or exhaust) steam from steam turbine
to obtain maximum efficiency and also to get the condensed steam in the form
of pure water, otherwise known as condensate, back to steam generator or
(boiler) as boiler feed water.
Tubes sea water
steam water (condensate)
vacuum is created due to steam / condensate volume difference
vacuum is maintained by constant cool water circulation through the
9.COOLING TOWERS :
The condensate (water) formed in the condenser after condensation is initially at
high temperature. This hot water is passed to cooling towers. It is a tower- or
building-like device in which atmospheric air (the heat receiver) circulates in
direct or indirect contact with warmer water (the heat source) and the water is
thereby cooled. A cooling tower may serve as the heat sink in a conventional
thermodynamic process, such as refrigeration or steam power generation, and
when it is convenient or desirable to make final heat rejection to atmospheric
air. Water, acting as the heat-transfer fluid, gives up heat to atmospheric air, and
thus cooled, is recirculated through the system, affording economical operation
of the process.
COOLING TOWER :
Inlet water temperature : 60 °C
Outlet water temperature : 35 °C
Output : 150 m3/h
Motor Power : 7.5 kW
10.ELECTROSTATIC PRECIPITATOR(ESP) :
It is a device which removes dust or other finely divided particles from flue gases
by charging the particles inductively with an electric field, then attracting them
to highly charged collector plates. Also known as precipitator. The process
depends on two steps. In the first step the suspension passes through an electric
discharge (corona discharge) area where ionization of the gas occurs. The ions
produced collide with the suspended particles and confer on them an electric
charge. The charged particles drift toward an electrode of opposite sign and are
deposited on the electrode where their electric charge is neutralized. The
phenomenon would be more correctly designated as electrode position from the
ESP ash collection 80 % (i.e.13.6 t/hr) of total ash generated.
Total height of ESP 27 m
Insulation Glass wool
Electric insulation material Porcelain insulator
Total efficiency 99.9%
1st field 80-85 %
2nd field 10-12 %
3rd and 4th field Rest
ESP ash collection 99.2 % of total ash generated.
First field : 1488
second field : 210
Third field : 42
fourth field : 8
Fifth field : 2
No. of electrical fields in series : 5
11.SMOKE STACK/CHIMNEY :
A chimney is a system for venting hot flue gases or smoke from
a boiler, stove, furnace or fireplace to the outside atmosphere. They are typically
almost vertical to ensure that the hot gases flow smoothly, drawing air into
the combustion through the chimney effect (also known as the stack effect). The
space inside a chimney is called a flue. Chimneys may be found in buildings,
steam locomotives and ships. In the US, the term smokestack (colloquially, stack)
is also used when referring to locomotive chimneys. The term funnel is generally
used for ship chimneys and sometimes used to refer to locomotive chimneys.
Chimneys are tall to increase their draw of air for combustion and to disperse
pollutants in the flue gases over a greater area so as to reduce the pollutant
concentrations in compliance with regulatory or other limits.
These are 220M tall RCC structures with single / multiple flues inside the
concrete shells (one flue per 330 MW units). The height of these chimneys varies
depending on the location of power plant.
Stage I Chimney: 220M (two flue’s inside the outer concrete shell)
Stage II Chimney: 275M (two flue’s inside the outer concrete shell)
Stage III Chimney: 275M (two flue’s inside the outer concrete shell)
Stage IV Chimney: 275M (three flue’s inside the outer concrete shell)
An alternator is an electromechanical device that converts mechanical energy
to alternating current electrical energy. Most alternators use a rotating magnetic
field. Different geometries - such as a linear alternator for use with stirling
engines - are also occasionally used. In principle, any AC generator can be called
an alternator, but usually the word refers to small rotating machines driven by
automotive and other internal combustion engines.
Generator is connected with the all HP, IP and LP turbines so when the turbines
rotates by the pressure of the steam the generator also rotate and due to magnetic
field it generates electricity.
In 330MW unit the generator is connected with one HP turbine ,one IP turbine
and one LP turbine but In 660MW unit the generator is connected with one HP
turbine, one IP turbine and two LP turbine.
Generator 330MW units Specifications
Active Output 330 MW
Apparent Output 388 MVA
Rated Terminal Voltage 24 KV+/- 5%
Rated Frequency 50 Hz +3% to -5%
Rated Power Factor 0.85 lagging
Phase Connection Star
Rated Speed 3000 rpm
Reference Standard IEC-34
Live Terminals brought out 3
Neutral Terminal brought out 3
Short Circuit ratio 0.60 min
Short time overload capability 150% for 15 sec
Class of Insulation for Stator & Rotor F
Temp. Rise of Stator/Rotor Limited to Class B
Cooling for Stator Core/Rotor Hydrogen
Over Speed 120% for 2 mins
3 Phase short circuit withstand time 3 Sec
Degree of Protection IP 54
Telephonic Harmonic interference factor Less than 1.5%
Inertia Constant of Generator 2 KW sec/ KVA
Type of Generator Earthing Earthed through
Cooling of Stator Winding DM Water
Type of Excitation Brushless without PMG
DM Cold water Temp. 38 °C
Cold Hydrogen gas temperature 46 °C
Generator (660MW units) Specifications
Manufacturer Dongfang Electric Machinery Ltd
Rated Capacity 776.5 MVA
Rated Power 660 MW
Rated stator voltage 22 kV, +/- 5%
Rated stator current 20377 A
Field Current 4476 A
No of Terminals 6
Frequency 50 Hz
Power factor 0.85 lag
Rated speed 3000 rpm
Wiring type Y - Y type ( Double star)
Cooling method Water, hydrogen
Cooling water of stator winding Directly Water cooled,
Flow 102 m³/Hr
Cooling Water Pressure 0.20 MPa
Cooling of stator core & rotor Directly hydrogen cooled
Insulation Class F
Excitation Terminal, Self, static excitation.
Generator rotating direction Clock wise
Rated Hydrogen Pressure 0.45 MPa (g) Max 0.5 MPa
Excitation Type Static Thyristor excitation
Short Circuit Ratio >= 0.5
Efficiency >= 98.8%
DC Resistance of stator winding/phase 0.001196 W at 15 °C
DC Resistance of field winding 0.077723 W at 15 °C
It is a device that transfers electric energy from one alternating-current circuit to
one or more other circuits, either increasing (stepping up) or reducing (stepping
down) the voltage. Uses for transformers include reducing the line voltage to
operate low-voltage devices and raising the voltage from electric generators so
that electric power can be transmitted over long distances. Transformers act
through electromagnetic induction; current in the primary coil induces current in
the secondary coil. The secondary voltage is calculated by multiplying the
primary voltage by the ratio of the number of turns in the secondary coil to that
in the primary.
After generating the electricity by the generator the electricity passes through
the transformers and this is how the electricity is generated.
The first phase of practical training has proved to be quiet fruitful. It provided an
opportunity for encounter with such hardworking engineers.
The architecture of the power plant the way various units are linked
and the way working of whole plant is controlled make the student realize that
engineering is not just learning the structured description and working of various
machines, but the greater part is of planning proper management.
It also provides an opportunities to learn low technology used at
proper place and time can cave a lot of labour But there are few factors that
require special attention. Training is not carried out into its tree sprit. It is
recommended that there should be some project specially meant for students
where presence of authorities should be ensured. There should be strict
monitoring of the performance of students and system of grading be improved on
the basis of work done.
However training has proved to be quite fruitful. It has allowed an
opportunity to get an exposure of the practical implementation to theoretical