it is the very important notes on : 1. Turbine 2. turbine component 3. princple of turbine 4.contruction of turbine 5.production process with hydroelectric and chp

1. BHAGWANT UNIVERSITY,
SIKAR ROAD, AJMER
TAKEN AT:
INDWELL
Construction Private Limited
SUBMITTED TO :
Prof O.P. Arora
HOD Of Mech.
Department
SUBMITTED BY :
Ambrish Pandey
Diploma (Final Year)
Mechanical
Roll No. 81601090005
GUIDED BY :
Er. Devesh Kumar Singh
(Asst. professor ME. Dept.)
&
Er. Sagar Sharma
SESSION 2016-2019
A VOCATIONAL TRAINING REPORT
(Asst. professor ME. Dept.)

3. ACKNOWLEDGEMENT
The internship opportunity I had with INDWELL Constructions Private
Limited was a great chance for learning and professional development.
Therefore, I consider myself as a very lucky individual as I was provided with
an opportunity to be a part of it. I am also grateful for having a chance to
meet so many wonderful people and professionals who led me through this
internship period.
I am very grateful to Mr. Vikash Ray (Sr Manager – HR ) for his valuable
feedback throughout the training period.
I am also thankful to other staff including shift in-charge and engineers for
their corporation during my vocational training period.
Finally, I thank PROFF. O.P. ARORA, HOD (Mechanical) Bhagwant University,
Ajmer.

4. INDWELL established in the year 1977 has successfully completed 4 decades of
powered excellence and we are marching ahead into another exciting phase.
This powered excellence was made possible only through sheer dedication,
hard work and discipline inculcated by Late Sri Kancherla Rama Rao, our
Founder & CMD. It is under his stewardship that the company has excelled in
the field of power and his expertise and experience has not only helped
INDWELL but also many other individuals, companies and customers for their
successful growth. We now at INDWELL have set higher levels of growth based
on the guiding principle of our founder
INDWELL - a name to be reckoned as a major Construction force in the field of
Erection, Testing & Commissioning of Turbo Generators, Boilers, LP/HP/Gas Piping,
Gas Turbine Sets, Hydro Turbines, Nuclear Turbines and their auxiliaries, Structural
works, Refineries and in the field of Overhauling, Maintenance Refurbishment,
Renovation, Upgradation and Modernisation of Power Station equipments from 1
M.W. to 800 M.W and beyond…….
The INDWELL is a combination of professional managerial talents, ability to
innovate sound business principle and a special technical know-how, integrity,
& hard work.
All about company

5. A thermal power station is a power plant in which the prime mover is steam
driven. Water is heated, turns into steam and spins a steam turbine which
drives an electrical generator. After it passes through the turbine, the steam is
undensed in a condenser and recycled to where it was heated; this is known
as a Rankine cycle. The greatest variation in the design of thermal power
stations is due to the different fuel sources. Some prefer to use the term
energy center because such facilities convert forms of heat energy into
electricity. Some thermal power plants also deliver heat energy for industrial
purposes, for district heating, or for desalination of water as well as delivering
electrical power. A large part of human CO2 emissions comes from fossil
fueled thermal power plants; efforts to reduce these outputs are various and
widespread. At present 54.09% or 93918.38 MW (Data Source CEA, as on
31/03/2011) of total electricity production in India is from Coal Based
Thermal Power Station. A coal based thermal power plant converts the
chemical energy of the coal into electrical energy. This is achieved by raising
the steam in the boilers, expanding it through the turbine and coupling the
turbines to the generators which converts mechanical energy into electrical
energy.
Abstract

6. TITLE Page No.
PROJECT…………………………………………………………………………………………………………..1
OBJECTIVES………………………………………………………………………………………………….….1
PLANT LAYOUT…………………………………………………………………………………………………2
PRODUCTION FLOW CHART………………………………………………………………………......3
PRODUCTION PROCESS……………………………………………………………………………….…..6
PRINCPLE………………………………………………………………………………………………………….6
TURBINE…………………………………………………………………………………………………………..24
CONTRUCTION OF TURBINE…………………………………………………………………………….28
CONCLUSION…………………………………………………………………………………………………...31
contents

7. To study the general concepts and working of thermal
power plant, and its components, especially turbine.
1. To learn the basic working of thermal power plants.
2. To learn about various components of the same.
3. To develop the understanding of the operation and
maintenance of turbines.
Objectives
Project
1

8. PLANT LAYOUT
Source :
Ambrish Pandey
2

9. Production Flow Chart
Procedure for production of electricity is based on modified Rankine cycle. The
four process of Rankine cycle as used in thermal power plants are as follows:-
1) Heat addition in boiler.
2) Adiabatic expansion in turbines.
3) Heat rejection in condenser and
4) Adiabatic compression in boiler feed pumps.
This may seem to be a simple enough process, but every step employs various
circuits to accomplish the required conditions for the fore told steps. Certain
circuits are as follows,
• Fuel and Ash Circuit.
• Air and Gas Circuit.
• Feed water and Steam Circuit.
• Cooling Water Circuit.
Various methods are employed to increase the efficiency of classical rankine cycle
by adding devices like air-preheater, economizer, superheater etc.
3

10. Above is the flow chart of production of electricity in a thermal power plant.
The input at boiler is the DM water and pulverized coal with air. The DM water
is prepared in the water treatment plant facility where it is deionized and
deaerated. It is prepared in the scale of neutral liquid i.e. 7ph, although,
slightly basic nature is used.
4

11. The coal is prepared at coal handling plant, where it first arrives in wagons. The coal is
taken out from wagons with the help of a machine known as wagon tippler. The coal is
the picked and sent to crushers, where it crushed and then to bunkers. From bunkers
the coal moves on to mills and is finely grounded to a pulverized form and the fed to
the boiler. Then this coal is fed to the boiler and combustion takes place. The energy of
the combustion is helpful in transforming the water into the steam. This steam is then
used to drive the turbine, the turbine shaft drives the generator. Hence electricity is
developed. The other product, which is ash, is fed into the ash treatment plant and
flue gasses are expelled in the atmosphere.
5

12. Production Process
Diagram of a typical coal-fired thermal power station
6

13. In a coal based power plant coal is transported from coal mines to the power plant
by railway in wagons or in a merry-go-round system. Coal is unloaded from the
wagons to a moving underground conveyor belt. This coal from the mines is of no
uniform size. So it is taken to the Crusher house and crushed to a size of 25mm.
From the crusher house the coal is either stored in dead storage( generally 20
days coal supply) which serves as coal supply in case of coal supply bottleneck or
to the live storage(8 hours coal supply) in the raw coal bunker in the boiler house.
Raw coal from the raw coal bunker is supplied to the Coal Mills by a Raw Coal
Feeder. The Coal Mills or pulverizer pulverizes the coal to 200 mesh size. The
powdered coal from the coal mills is carried to the boiler in coal pipes by high
pressure hot air. The pulverized coal air mixture is burnt in the boiler in the
combustion zone. Generally in modern boilers tangential firing system is used i.e.
the coal nozzles/ guns form tangent to a circle. The temperature in fire ball is of
the order of 1300 deg.C. The boiler is a water tube boiler hanging from the top.
Water is converted to steam in the boiler and steam is separated from water in
the boiler Drum. The saturated steam from the boiler drum is taken to the Low
Temperature Superheater, Platen Superheater and Final Superheater respectively
for superheating. The superheated steam from the final superheater is taken to
the High Pressure
7

14. Steam Turbine (HPT). In the HPT the steam pressure is utilized to rotate the
turbine and the resultant is rotational energy. From the HPT the out coming
steam is taken to the Reheater in the boiler to increase its temperature as the
steam becomes wet at the HPT outlet. After reheating this steam is taken to
the Intermediate Pressure Turbine (IPT) and then to the Low Pressure Turbine
(LPT). The outlet of the LPT is sent to the condenser for condensing back to
water by a cooling water system. This condensed water is collected in the
Hotwell and is again sent to the boiler in a closed cycle. The rotational energy
imparted to the turbine by high pressure steam is converted to electrical
energy in the Generator.
8

15. Principle
Coal based thermal power plant works on the principal of Modified Rankine
Cycle.
9

16. The conversion from coal to electricity takes place in three stages.
Stage 1
The first conversion of energy takes place in the boiler. Coal is burnt in the
boiler furnace to produce heat. Carbon in the coal and Oxygen in the air
combine to produce Carbon Dioxide and heat.
Stage 2
The second stage is the thermodynamic process.The heat from
combustion of the coal boils water in the boiler to produce steam. In
modern power plant, boilers produce steam at a high pressure and
temperature.The steam is then piped to a turbine.The high pressure steam
impinges and expands across a number of sets of blades in the turbine.
The impulse and the thrust created rotates the turbine.The steam is then
condensed and pumped back into the boiler to repeat the cycle.
Stage 3
In the third stage, rotation of the turbine rotates the generator rotor to
produce electricity based of Faraday’s Principle of electromagnetic
induction.
Check out this series describing the layout of the thermal power plant.
10

17. Components of Coal Fired Thermal Power Station
In coal-fired power stations, the raw feed coal from the coal storage area is first
crushed into small pieces and then conveyed to the coal feed hoppers at the boilers.
The coal is next pulverized into a very fine powder. The pulverizers may be ball mills,
rotating drum grinders, or other types of grinders.
Fuel preparation system
External fans are provided to give sufficient air for combustion. The forced draft fan
takes air from the atmosphere and, first warming it in the air preheater for better
combustion, injects it via the air nozzles on the furnace wall.
Air path
The induced draft fan assists the FD fan by drawing out combustible gases from the
furnace, maintaining a slightly negative pressure in the furnace to avoid backfiring
through any opening.
11

18. Boiler furnace and steam drum
Once water inside the boiler or steam generator, the process of adding the latent
heat of vaporization or enthalpy is underway. The boiler transfers energy to the
water by the chemical reaction of burning some type of fuel.
The water enters the boiler through a section in the convection pass called the
economizer. From the economizer it passes to the steam drum. Once the water enters
the steam drum it goes down the downcomers to the lower inlet waterwall headers.
From the inlet headers the water rises through the waterwalls and is eventually
turned into steam due to the heat being generated by the burners located on the
front and rear waterwalls (typically). As the water is turned into steam/vapor in the
waterwalls, the steam/vapor once again enters the steam drum. The steam/vapor is
passed through a series of steam and water separators and then dryers inside the
steam drum. The steam separators and dryers remove water droplets from the steam
and the cycle through the waterwalls is repeated. This process is known as natural
circulation.
The boiler furnace auxiliary equipment includes coal feed nozzles and igniter guns,
soot blowers, water lancing and observation ports (in the furnace walls) for
observation of the furnace interior. Furnace explosions due to any accumulation of
combustible gases after a trip-out are avoided by flushing out such gases from the
combustion zone before igniting the coal.
12

19. The steam drum (as well as the superheater coils and headers) have air vents and
drains needed for initial startup. The steam drum has internal devices that removes
moisture from the wet steam entering the drum from the steam generating tubes. The
dry steam then flows into the superheater coils.
Superheater
Coal based power plants can have a superheater and/or reheater section in the steam
generating furnace. Nuclear-powered steam plants do not have such sections but
produce steam at essentially saturated conditions. In a coal based plant, after the
steam is conditioned by the drying equipment inside the steam drum, it is piped from
the upper drum area into tubes inside an area of the furnace known as the
superheater, which has an elaborate set up of tubing where the steam vapor picks up
more energy from hot flue gases outside the tubing and its temperature is now
superheated above the saturation temperature. The superheated steam is then piped
through the main steam lines to the valves before the high pressure turbine.
Reheater
Power plant furnaces may have a reheater section containing tubes heated by hot flue
gases outside the tubes. Exhaust steam from the high pressure turbine is rerouted to
go inside the
.
13

20. reheater tubes to pickup more energy to go drive intermediate or lower pressure
turbines. This is what is called as thermal power
Fly ash collection
Fly ash is captured and removed from the flue gas by electrostatic precipitators or
fabric bag filters (or sometimes both) located at the outlet of the furnace and
before the induced draft fan. The fly ash is periodically removed from the
collection hoppers below the precipitators or bag filters. Generally, the fly ash is
pneumatically transported to storage silos for subsequent transport by trucks or
railroad cars.
Bottom ash collection and disposal
At the bottom of the furnace, there is a hopper for collection of bottom ash. This
hopper is always filled with water to quench the ash and clinkers falling down from
the furnace. Some arrangement is included to crush the clinkers and for conveying
the crushed clinkers and bottom ash to a storage site.
14

21. Boiler make-up water treatment plant and storage
Since there is continuous withdrawal of steam and continuous return of condensate
to the boiler, losses due to blowdown and leakages have to be made up to maintain
a desired water level in the boiler steam drum. For this, continuous make-up water is
added to the boiler water system. Impurities in the raw water input to the plant
generally consist of calcium and magnesium salts which impart hardness to the
water. Hardness in the make-up water to the boiler will form deposits on the tube
water surfaces which will lead to overheating and failure of the tubes. Thus, the salts
have to be removed from the water, and that is done by a water demineralising
treatment plant (DM). A DM plant generally consists of cation, anion, and mixed bed
exchangers. Any ions in the final water from this process consist essentially of
hydrogen ions and hydroxide ions, which recombine to form pure water. Very pure
DM water becomes highly corrosive once it absorbs oxygen from the atmosphere
because of its very high affinity for oxygen.
The capacity of the DM plant is dictated by the type and quantity of salts in the raw
water input. However, some storage is essential as the DM plant may be down for
maintenance. For this purpose, a storage tank is installed from which DM water is
continuously withdrawn for boiler make-up. The storage tank for DM water is made
from materials not affected by corrosive water, such as PVC.
15

22. The piping and valves are generally of stainless steel. Sometimes, a steam
blanketing arrangement or stainless steel doughnut float is provided on top of the
water in the tank to avoid contact with air. DM water make-up is generally added at
the steam space of the surface condenser (i.e., the vacuum side). This arrangement
not only sprays the water but also DM water gets deaerated, with the dissolved
gases being removed by an air ejector attached to the condensor
Steam turbine-driven electric generator
Rotor of a modern steam turbine, used in a power station
16

23. The steam turbine-driven generators have auxiliary systems enabling them to work
satisfactorily and safely. The steam turbine generator being rotating equipment
generally has a heavy, large diameter shaft. The shaft therefore requires not only
supports but also has to be kept in position while running. To minimise the frictional
resistance to the rotation, the shaft has a number of bearings. The bearing shells, in
which the shaft rotates, are lined with a low friction material like Babbitt metal. Oil
lubrication is provided to further reduce the friction between shaft and bearing
surface and to limit the heat generated.
Barring gear
Barring gear (or “turning gear”) is the mechanism provided to rotate the turbine
generator shaft at a very low speed after unit stoppages. Once the unit is “tripped”
(i.e., the steam inlet valve is closed), the turbine coasts down towards standstill. When
it stops completely, there is a tendency for the turbine shaft to deflect or bend if
allowed to remain in one position too long. This is because the heat inside the turbine
casing tends to concentrate in the top half of the casing, making the top half portion
of the shaft hotter than the bottom half. The shaft therefore could warp or bend by
millionths of inches.
This small shaft deflection, only detectable by eccentricity meters, would be enough
to cause damaging vibrations to the entire steam turbine generator unit when it is
restarted. The shaft is therefore automatically turned at low speed by the barring gear
until it has cooled sufficiently to permit a complete stop. 17

24. Condenser
Diagram of a typical water-cooled surface condenser
The surface condenser is a shell and tube heat exchanger in which cooling water is
circulated through the tubes. The exhaust steam from the low pressure turbine
enters the shell where it is cooled and converted to condensate (water) by flowing
over the tubes as shown in the adjacent diagram. Such condensers use steam
ejectors or rotary motor-driven exhausters for continuous removal of air and gases
from the steam side to maintain vacuum.
18

25. For best efficiency, the temperature in the condenser must be kept as low as practical
in order to achieve the lowest possible pressure in the condensing steam. Since the
condenser temperature can almost always be kept significantly below 100 °C where
the vapor pressure of water is much less than atmospheric pressure, the condenser
generally works under vacuum. Thus leaks of noncondensible air into the closed loop
must be prevented. Plants operating in hot climates may have to reduce output if
their source of condenser cooling water becomes warmer; unfortunately this usually
coincides with periods of high electrical demand for air conditioning.
The condenser generally uses either circulating cooling water from a cooling tower to
reject waste heat to the atmosphere, or once-through water from a river, lake or
ocean.
Feedwater heater
In the case of a conventional steam-electric power plant utilizing a drum boiler, the
surface condenser removes the latent heat of vaporization from the steam as it
changes states from vapour to liquid. The heat content (joules or Btu) in the steam is
referred to as enthalpy. The condensate pump then pumps the condensate water
through a Air ejector condenser and Gland steam exhauster condenser. From there
the condensate goes to the deareator where the condenstae system ends and the
Feedwater system begins
19

26. Preheating the feedwater reduces the irreversibilities involved in steam generation
and therefore improves the thermodynamic efficiency of the system.This reduces
plant operating costs and also helps to avoid thermal shock to the boiler metal
when the feedwater is introduced back into the steam cycle.
Deaerator
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 feedwater. A deaerator typically includes a
vertical, domed deaeration section mounted on top of a horizontal cylindrical
vessel which serves as the deaerated boiler feedwater storage tank
Cooling tower
A cooling tower is a heat rejection device, which extracts waste heat to the
atmosphere though the cooling of a water stream to a lower temperature.
20

27. The type of heat rejection in a cooling tower is termed “evaporative” in that it allows a
small portion of the water being cooled to evaporate into a moving air stream to
provide significant cooling to the rest of that water stream. The heat from the water
stream transferred to the air stream raises the air’s temperature and its relative
humidity to 100%, and this air is discharged to the atmosphere. Evaporative heat
rejection devices such as cooling towers are commonly used to provide significantly
lower water temperatures than achievable with “air cooled” or “dry” heat rejection
devices, like the radiator in a car, thereby achieving more cost-effective and energy
efficient operation of systems in need of cooling
The cooling towers are of two types: -
1. Natural Draft Cooling Tower
2. Mechanical Draft Cooling Tower
i. Forced Draft cooling tower
ii. Induced Draft cooling tower
iii. Balanced Draft cooling tower
21

28. Generator heat dissipation
The electricity generator requires cooling to dissipate the heat that it generates.
While small units may be cooled by air drawn through filters at the inlet, larger units
generally require special cooling arrangements. Hydrogen gas cooling, in an oil-
sealed casing, is used because it has the highest known heat transfer coefficient of
any gas and for its low viscosity which reduces windage losses. This system requires
special handling during start-up, with air in the chamber first displaced by carbon
dioxide before filling with hydrogen. This ensures that the highly flammable
hydrogen does not mix with oxygen in the air.
The hydrogen pressure inside the casing is maintained slightly higher than
atmospheric pressure to avoid outside air ingress. The hydrogen must be sealed
against outward leakage where the shaft emerges from the casing. Mechanical seals
around the shaft are installed with a very small annular gap to avoid rubbing
between the shaft and the seals. Seal oil is used to prevent the hydrogen gas leakage
to atmosphere.
The generator also uses water cooling. Since the generator coils are at a potential of
about 22 kV and water is conductive, an insulating barrier such as Teflon is used to
interconnect the water line and the generator high voltage windings. Demineralized
water of low conductivity is used.
22

29. Generator high voltage system
The generator voltage ranges from 11 kV in smaller units to 22 kV in larger units. The
generator high voltage leads are normally large aluminum channels because of their
high current as compared to the cables used in smaller machines. They are enclosed in
well-grounded aluminum bus ducts and are supported on suitable insulators.
Battery supplied emergency lighting and communication
Other systems
Monitoring and alarm system
Most of the power plant operational controls are automatic. However, at times,
manual intervention may be required. Thus, the plant is provided with monitors and
alarm systems that alert the plant operators when certain operating parameters are
seriously deviating from their normal range.
A central battery system consisting of lead acid cell units is provided to supply
emergency electric power, when needed, to essential items such as the power plant’s
control systems, communication systems, turbine lube oil pumps, and emergency
lighting. This is essential for a safe, damage-free shutdown of the units in an
emergency situation.
23

30. TURBINES
A steam turbine is a mechanical device that extracts and converts it into rotary
motion. Its modern manifestation was invented by sir charles Parsons in 1884.
It has almost completely replaced the reciprocating piston steam engine primarily
because of its greater thermal efficiency and higher power-to-weight ratio
because the turbine generator rotary motion it is particularly suited to be used to
drive an electricity generation –about 80% of all electricity generation in the world
is by use of steam turbines.
TYPES
1.IMPULSE TURBINE
2.REACTION TURBINES
1.IMPULSE TURBINE
An impulse turbine has fixed nozzles that orient the steam flow into high speed
jets. These jets contain significant kinetic energy, which the rotor blades, shaped
like buckets, convert into shaft rotation as the steam jet changes direction. A
pressure drop occurs across only the stationary blades, with a net increase in
steam velocity across the stage.
24

31. As the steam flows through the nozzle its pressure falls from inlet pressure to the
exit pressure (atmospheric pressure, or more usually, the condenser vacuum). Due
to this higher ratio of expansion of steam in the nozzle the steam leaves the nozzle
with a very high velocity. The steam leaving the moving blades has a large portion of
the maximum velocity of the steam when leaving the nozzle. The loss of energy due
to this higher exit velocity is commonly called the "carry over velocity" or "leaving
loss".
REATION TURBINES
In the reaction turbine, the rotor blades themselves are arranged to form convergent
nozzles. This type of turbine makes use of the reaction force produced as the steam
accelerates through the nozzles formed by the rotor. Steam is directed onto the rotor
by the fixed vanes of the stator. It leaves the stator as a jet that fills the entire
circumference of the rotor. The steam then changes direction and increases its speed
relative to the speed of the blades. A pressure drop occurs across both the stator
and the rotor, with steam accelerating through the stator and decelerating through
the rotor, with no net change in steam velocity across the stage but with a decrease
in both pressure and temperature, reflecting the work performed in the driving of
the rotor.
25

32. Operation and maintenance
When warming up a steam turbine for use, the main steam stop valves (after the
boiler) have a bypass line to allow superheated steam to slowly bypass the valve
and proceed to heat up the lines in the system along with the steam turbine.
Also, a turning gear is engaged when there steam to the turbine to slowly rotate
the turbine to ensure even heating to prevent uneven expansion. After first
rotating the turbine by the turning gear, allowing time for the rotor to assume a
straight plane (no bowing), then the turning gear is d the turbine, first to the
astern blades then to the ahead blades slowly rotating the turbine at 10 to 15
RPM to slowly warm the turbine.
A modern steam turbine generator installation
26

33. Problems with turbine are now rare and maintainance requirments are relatively
small. Any imbalance of rotor can lead to vibration, which in extreme cases can
lead to a blade letting go and punching straight through the casing. It is, however,
essential that the turbine be turned with dry steam - that is, superheated steam
with a minimal liquid water content. If water gets into the steam and is blasted
onto the blades (moisture carryover), rapid impingement and erosion of the blades
can occur leading to imbalance and catastrophic failure. Also, water entering the
blades will result in the destruction of the thrust bearing for the turbine shaft. To
prevent this, along with controls and baffles in the boilers to ensure high quality
steam, condensate drains are installed in the steam piping leading to the turbine
Speed regulation
The control of a turbine with a governor is essential, as turbines need to be run up
slowly, to prevent damage while some applications (such as the generation of
alternating current electricity) require precise speed control. Uncontrolled
acceleration of the turbine rotor can lead to an overspeed trip, which causes the
nozzle valves that control the flow of steam to the turbine to close. If this fails then
the turbine may continue accelerating until it breaks apart often
Spectacularly Turbines are expensive to make, requiring precision manufacture and
special quality materials. During normal operation in synchronization with the
electricity network, power plants are governed with a five percent droop speed
control. 27

34. This means the full load speed is 100% and the no-load speed is 105%. This is
required for the stable operation of the network without hunting and drop-outs of
power plants. Normally the changes in speed are minor. Adjustments in power output
are made by slowly raising the droop curve by increasing the spring pressure on a
centrifugal governor. Generally this is a basic system requirement for all power plants
because the older and newer plants have to be compatible in response to the
instantaneous changes in frequency without depending on outside communication.
Construction
The turbine is a tandem compound machine which separates the hp, ip and lp
sections. sections. The hp section is single flow while ip & lp are dual flow. The
turbine rotor and generator rotor are connected by rigid couplings.
The hp turbine is throttle controlled, the steam is entered ahead of blades via
combination of two stop and control valves. A swing check valve is installed
between the exhaust and the reheater, to prevent the flow of hot steam back into
the hp turbine. The steam coming from reheater is passed to ip turbine via
combination of two reheat stop and control valves. Cross around pipes connect the
ip and lp cylinders. Connections are provided at several point of turbine for feed
water extraction.
HP TURBINE
The outer casing of turbine is of barrel type, which has neither axial nor a radial
flange. This prevents mass concentration which would cause high thermal stresses.
The inner turbine is axially split, which is accommodate thermal expansion.
28

35. LP TURBINE
The LP turbine is dual flow. It has a three shell design which are horizontally split and
are of rigid welded construction. The innermost shell, which carries first row of
stationary blades, is supported, so as to allow the thermal expansion of inner shell
within intermediate shell.
BLADING
The entire turbine provided with reaction blading. The moving blades of HP and IP
turbine and the blades of front rows of LP turbine are designed with integrally milled
T-roots and shrouds. The last stages of LP turbine are fitted with a twisted drop-
forged moving blades with firtre roots engaging in corresponding grooves in rotor.
Highly stressed guide blades of HP and IP parts have inverted T roots and shrouding
are machined from one piece like the moving blades. The other guide blades have
inverted L roots and riveted shrouding. The last three stages of IP turbine have
fabricated guide blades.
BEARINGS
The HP rotor is supported on two bearings, a journal bearing on its front end and a
combined journal and thrust bearing immediately next to the coupling of the ip
rotor.
29

36. The IP and LP rotors have journal bearings at each of their rear ends. The combined
journal and thrust bearings incorporates a journal bearing and a thrust bearing
which takes up residual thrust from both direction. The bearing metal temperatures
are measured by thermocouples directly under the babit lining. The temperature of
the bearing is measured in the two opposite thrust pads on each side.
All shaft seals, which seal the steam from the outer atmosphere are axial flow
labyrinth type seals. They consists of a large number of thin strips of seals which,
in hp and ip turbine are caulked alternately into the grooves in the shafts and the
surrounding seal rings. In the lp turbine, the seals are caulked only into seal rings.
Seal strips of similar design are also used to seal the radial blade tip clearences
SHAFT SEAL ANF BLADE TIP SEALING
VALVES
. The hp turbine is fitted with two main stop and control valves. One main stop valve
and control valve with stems arranged at right angles to each other, are combined in
the common body. The main stop valves are single seat spring action valves. The
control valves are also single seat valves but use diffuser a reduce the pressure
losses.
The main, reheat and control valves are supported free to move in thermal
expansion. All the valves are operated by individual hydraulic servomotors. 30

37. Conclusion
From all the study it can be concluded that the INDWELL CONTRUCTION PRIVATE
LIMITED organized unit with the latest machinery available.
The turbine is a very sophisticated assembly of machinery which requires specific
conditions of steam temperature and pressure to work efficiently. Any alteration of
the specific requirements may prove hazardous to the turbine.
Another interesting yet worrying fact is the quantity of coal consumed, which
approximately 10800 tone per day. The level of pollution is always controlled
according the established norms, but still I consider it to be quite enough. Well,
efforts are always underway interducing the pollution and improving the efficiency
of the plant.
All in all, a thermal power project is very large establishment with many
components and it awes me to see how all the components work in a synchronized
manner.
31