projects on ATPS

1. SUMMER TRAINING REPORT AT UTTPAR PRADESH RAJAY VIDUAT UTPADAN
NIGAM LIMITED ANPARA SONEBHADRA
ON
“THERMEL POWER PLANT”
Submitted for partial fulfillment of award of
BACHELOR OF TECHNOLOGY
IN
MECHANICAL ENGINEERING
UNDER THE SUPERVISION OF:- COLLEGE INCHARGE:-
ER.SAMIR BHATNAGAR DR. B D SAHOO
(EXECUTIVE ENGINEER B.M.D. I) (H.O.D OF ME DEPARTMENT)
SUBMITTED BY:-
RAGHWENDRA KU. PATHAK
B.TECH ME 3rd
YEAR
REGD. NO. 1101320106

2. Acknowledgment
The result of all engineering efforts whatever from they take a direct outcome of not just
an individual’s thinking but represents the organization. The same view holds good this
seminar report.
I extended my sincere gratitude towards Er. SAMIR BHATNAGAR SIR (EXECUTIVE
ENGINEERING B.M.D.I, BTPS) for giving us invaluable knowledge & Technical guidance.
I would like to thanks Er. SAMIR BHATNAGAR SIR (EXECUTIVE ENGINEER B.M.D.I, BTPS) for
giving me their kind co-operation & inspiration to do my seminar work.
I also thanks all the staff members and my friends for their endless Help and support.
NAME OF THE STUDENT:-
RAGHWENDRA KU. PATHAK
REGD.NO. 1101320106
BRANCH:-ME 3rd
YEAR

3. Certificate
This is certified that RAGHWENDRA KU. PATHAK student of Mechanical Engineering from
Aryan Institute of Engineering & Technology, Bhubaneswar has carried out his summer
training work during “7 MAY 2014 to 6 JUNE 2014” presented in this report entitled
“(THERMAL POWER PLANT)” under my supervision of Er. SAMIR BHATNAGAR (EXECUTIVE
ENGINEER B.M.D.I BTPS) and his entire team.
Er. SAMIR BHATNAGAR
(EXECUTIVE ENGINEER B.M.D.I BTPS)

4. Abstract
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 condensed 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.

5. Contents
PROJECT ……………………………………………………………………………………1
OBJECTIVES……………………………………………………………………………......2
BRIEF HISTORY/INTRODUCTION OF ORGANIZATION……………………………...3
ORGANIZATIONAL CHART……………………………………………………………...5
PLANT LAYOUT…………………………………………………………………………...6
PRODUCTS AND SPECIFICATION………………………………………………………7
PRODUCT FLOW CHART…………………………………………………………………8
CHRONOLOGICAL TRAINING DIARY…………………………………………………11
PRODUCTION PROCESS…………………………………………………………………12
TURBINE……………………………………………………………………………………23
210 MW TURBINES IN PARICCHA………………………………………………………32
MARKETING STRATEGIES………………………………………………………………37
DIVERSIFICATION OR EXPANSION……………………………………………………38
SUGGESTIONS……………………………………………………………………………..39
CONCLUSION……………………………………………………………………………....40

6. Project
To study the general concepts and working of thermal power
plant, and its components, especially turbine.
1

7. Brief history
This is a project run under Uttar Pradesh Rajya Vidhyut Utpadan Nigam Ltd.UPRVUNL is wholly
owned state thermal power utility with present generating capacity of 4082MW, operating 5
Thermal Power Stations within Uttar Pradesh. Poised to contribute in the growth of state, we're
in the process of adding further 2000 MW capacity to our existing fleet by year 2012.
The name of this power project is paricha thermal power project its foundation war laid in 1979
and it started producing electricity in 1983. It is a state owned semi government project. It has
four units which are generating electricity. Two no of 250MW which are likely to be completed
tip to year 2011.
Total installed capacity of the plant at present is 640 mw. The total installed capacity of the
plant will be 1140 mw in the year 2011 presently it is thermal power project of UPRVUNL. This
project is thermal based power project in which combustion of coal is used to convert
water into steam and then steam is used to rotate the turbine the rotation of turbine drives an
a.c. generator, thereby producing a.c. power. The entire thermal power project needs
continuous supply of water and thus they are built near Betwa River. A dam has been
constructed for this purpose of collection of water, by the name of parichadam. Coal is also
required for this project and it is supplied from mines of BCCL, ECL. At present, four units of
Parichha are generating 640 mw of electricity. Uttar Pradesh Rajya Vidyut Utpadan Nigam Ltd.
was constituted on 25 August 1980 under the company’s act 1956 for construction of new
thermal power projects in the state sector. On 14th Jan 2000, in accordance to up state
electricity reforms acts 1999, UP state electricity board, till then responsible for generation,
transmission and distribution of power within the state of Uttar Pradesh, was unbundled and
operations of the state sector thermal power stations was handed over to UPRVUNL.
2

8. Products and Specifications
Following two are the main products in a thermal power plant:-
1) Electricity
Electricity is produced at approximately 15.5 KV after which it is stepped up to 220 KV
for reduction in losses due to transmission. Then it is connected to the grid for supply. The main
client for purchasing electricity of UPRVUNL is UPPCL which is UTTAR PRADESH POWER
CORPORATION LIMITED.
2) Ash:-
Ash is the byproduct of coal after its combustion. It can be categorized in two parts:-
A) Fly ash, which is sold to cement manufacturing organizations like Diamond and Satna.
Earlier they were given away to the same, but since posses certain value; they’re now being sold
to them which generates revenues up to twenty lakhs.
B) Ash slurry, it is a waste product which is generally provided to construction companies for
road-filling etc.
3

9. Product 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.
4

10. 5

11. 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 deareated. It prepared in the scale
of neutral liquid i.e. 7ph, although, slightly basic nature is used.
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.
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12. Chronological training diary
7th
May 2014 to 13th
May 2014
This week was dedicated to familiarization with power plant, a basic understanding was
developed of the flow of various elements in the production cycle, like flow of steam, DM water,
clarified cooling water, coal and flue gases.
14th
May 2014 to 20th
May 2014
This week was dedicated in the study of installed 210 MW turbines. Various concepts regarding
turbine were studied like axial shift, casing expansion, barring gear mechanism, synchronization
of turbine during startup, etc.
21th
May2014 to 27th
May 2014
We spent this week with familiarization with coal handling plant, learning flow of coal in it and
the methods and processes of converting large sized coal to a form of powder.
28th
May2014 to 6th
june 2014
This time was spent in understanding the importance and working of ash handling plant and
water treatment plant.
7

13. Production process
Diagram of a typical coal-fired thermal power station
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 formatngent 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.
8

14. The superheated steam from the final superheater is taken to the High Pressure 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 hot well 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.
Principal
Coal based thermal power plant works on the principal of Modified Rankine Cycle.
9

15. ComponentsofCoalFiredThermalPowerStation:
Fuelpreparationsystem
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.
Airpath
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. 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.
Boilerfurnaceandsteamdrum
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 down comers to the lower inlet water
wall headers. From the inlet headers the water rises through the water walls and is eventually
turned into steam due to the heat being generated by the burners located on the front and rear
water walls (typically). As the water is turned into steam/vapor in the water walls, 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 water walls 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. 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.
10

16. 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
reheater tubes to pickup more energy to go drive intermediate or lower pressure turbines. This
is what is called as thermal power.
Flyashcollection
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.
Bottomashcollectionanddisposal
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.
Boilermake-upwatertreatmentplantandstorage
Since there is continuous withdrawal of steam and continuous return of condensate to the
boiler, losses due to blow down 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.
11

17. 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. 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 de aerated, with the dissolved gases being removed by
an air ejector attached to the condenser.
Steamturbine-drivenelectricgenerator
Rotor of a modern steam turbine, used in a power station
12

18. 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 minimize 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.
Barringgear
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
(about one percent rated speed) by the barring gear until it has cooled sufficiently to permit a
complete stop.
Condenser
Diagram of a typical water-cooled surface condenser
13

19. 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. 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 non-
condensible 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.
Feedwaterheater
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 Feed water system begins. Preheating the feed water
reduces the irreversibility’s 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 feed water is introduced back into the steam
cycle.
Deaerator
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 feedwater. A deaerator typically includes a vertical, domed aeration
section mounted on top of a horizontal cylindrical vessel which serves as the deaerated
boiler feedwater storage tank.
14

20. Coolingtower
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. 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.
Thecoolingtowersareoftwotypes:-
1. Natural Draft Cooling Tower
2. Mechanized Draft Cooling Tower
i. Forced Draft cooling tower
ii. Induced Draft cooling tower
iii. Balanced Draft cooling tower
15

21. Auxiliarysystems
Oil system
An auxiliary oil system pump is used to supply oil at the start-up of the steam turbine
generator. It supplies the hydraulic oil system required for steam turbine’s main inlet steam
stop valve, the governing control valves, the bearing and seal oil systems, the relevant hydraulic
relays and other mechanisms. At a preset speed of the turbine during start-ups, a pump driven
by the turbine main shaft takes over the functions of the auxiliary system.
Generatorheatdissipation
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. De mineralized water of
low conductivity is used.
Generatorhighvoltage 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. The generator high
voltage channels are connected to step-up transformers for connecting to a high voltage
electrical substation (of the order of 115 kV to 520 kV) for further transmission by the local
power grid. The necessary protection and metering devices are included for the high voltage
leads. Thus, the steam turbine generator and the transformer form one unit. In smaller units,
generating at 11 kV, a breaker is provided to connect it to a common 11 kV bus system.
16

22. Othersystems
Monitoringandalarmsystem
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.
Batterysuppliedemergencylightingandcommunication
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.
17

23. TURBINES
A steamturbine is a mechanical device that extracts thermal energy from pressurized steam,
converts it into rotary motion. Its modern manifestation was invented by sir Charles
1884.
It has almost completely replace
greater thermal efficiency and hi
rotary motion, it is particularly suited
all electricity generation in the worl
TYPES
Schematic operation of a steam turbine generator system
l device that extracts thermal energy from pressurized steam,
n. Its modern manifestation was invented by sir Charles
almost completely replaced the reciprocating piston steam engine primarily because of it
greater thermal efficiency and higher power-to-weight ratio. Because the turbine generates
motion, it is particularly suited to be used to drive an electrical generator
electricity generation in the world is by use of steam turbines.
Schematic operation of a steam turbine generator system
l device that extracts thermal energy from pressurized steam, and
n. Its modern manifestation was invented by sir Charles Parsons in
d the reciprocating piston steam engine primarily because of it
weight ratio. Because the turbine generates
enerator-about 80% of
18

24. Steam turbines are made in a variety o f sizes ranging from small <1 hp (<0.75 kw) units (rare)
used as mechanical drives for pumps, compressors and other shaft driven equipments , to
2,000,000 hp (1,500,000 kW) turbines used to generate electricity. There are several
classifications for modern steam turbines.
Steam supply and exhaust conditions
These types include condensing, non condensing, reheat, extraction and induction. None
condensing or back pressure turbines are most widely used for process steam applications. The
exhaust pressure is controlled by a regulating valve to suit the needs of the process
steam pressure. These are commonly found at refineries, district heating units, pulp and paper
plants, and desalination facilities where large amounts of low pressure process steam are
available. Condensing turbines are most commonly found in electrical power plants. These
turbines exhaust steam in a partially condensed state, typically of a quality near 90%, at a
pressure well below atmospheric to a condenser .Reheat turbines are also used almost
exclusively in electrical power plants. In a reheat turbine, steam flow exits from a high pressure
section of the turbine and is returned to the boiler where additional superheat is added. The
steam then goes back into an intermediate pressure section of the turbine and continues its
expansion .Extracting type turbines are common in all applications. In an extracting type
turbine, steam Is released from various stages of the turbine, and used for industrial process
needs or sent to boiler feed water heaters to improve overall cycle efficiency. Extraction flows
may be controlled with a valve, or left uncontrolled. Induction turbines introduce low pressure
steam at an intermediate stage to produce additional power.
MountingofasteamturbineproducedbySiemens
19

25. Casing or shaft arrangements
These arrangements include single casing, tandem compound and cross compound turbines.
Single casing units are the most basic style where a single casing and shaft are coupled to a
generator. Tandem compound are used where two or more casings are directly coupled
together to drive a single generator.
A cross compound turbine arrangement features two or more shafts not in line driving two or
more generators that often operate at different speeds. A cross compound turbine is typically
used for many large applications. Principal of design and operation An ideal steam turbine is
considered to be an isentropic process, or constant entropy process, in which the entropy of
the steam entering the turbine is equal to the entropy of the steam leaving the turbine. No
steam turbine is truly “isentropic”, however, with typical isentropic efficiencies ranging from
20%-90% based on the application of the turbine. The interior of a turbine comprises several
sets of blades, or “buckets” as they are more commonly referred to. One set of stationary
blades is connected to the casing and one set of rotating blades is connected to the shaft. The
sets intermesh with certain minimum clearances, with the size and configuration of sets varying
to efficiently exploit the expansion of steam at each stage.
Turbine efficiency
Schematicdiagramoutliningthedifferencebetweenanimpulseandareactionturbine
20

26. To maximize turbine efficiency the steam is expanded, doing work, in a number of stages .These
stages are characterized by how the energy is extracted from them and are known as either
impulse or reaction turbines. Most steam turbines use a mixture of the reaction and impulse
steam turbines use a mixture of the reaction and impulse design; each stage behaves as either
one or other, but the overall turbine uses both. Typically, higher pressure sections are impulse
type and lower pressure stages are reaction type.
Impulse turbines
An impulseturbinehas 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. 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".
Types of turbine blades
21

27. REACTIONTURBINES
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.
22

28. 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
system along with the steam turbine. Also, a turning gear is engaged when there is no 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 disengaged and steam is admitted to the turbine, first to the astern
blades then to the ahead blades slowly rotating the
Problems with turbines are now are and maintenance requirements are relatively small. Any
imbalance of the rotor can lead to vibration, which in extreme cases can lead to a
go and punching straight through the casing. It is, however, essenti
with dry steam –that is, superheated steam
into the steam and is blasted on to the blades (moisture carryover, rapid impingement and
erosion of the blades can occur leading to i
entering the blades this, 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.
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 is no steam to the
turbine to slowly rotate the turbine to ensure even heating to prevent uneven expansion. After first
turning gear, allowing time for the rotor to assume a straight plane (no
bowing) , then the turning gear is disengaged and steam is admitted to 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
Problems with turbines are now are and maintenance requirements are relatively small. Any
imbalance of the rotor can lead to vibration, which in extreme cases can lead to a
go and punching straight through the casing. It is, however, essential that the turbine be turned
that is, superheated steam with minimal liquid water content. If water gets
into the steam and is blasted on to the blades (moisture carryover, rapid impingement and
erosion of the blades can occur leading to imbalance and catastrophic failure. Also, water
entering the blades this, 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,
ains are installed in the steam piping leading to the turbine.
When warming up a steam turbine for use, the main steam stop valves (after the boiler) have a bypass
to heat up the lines in the
system along with the steam turbine. Also, a turning gear is engaged when there is no steam to the
turbine to slowly rotate the turbine to ensure even heating to prevent uneven expansion. After first
turning gear, allowing time for the rotor to assume a straight plane (no
bowing) , then the turning gear is disengaged and steam is admitted to the turbine, first to the astern
slowly warm the turbine.
Problems with turbines are now are and maintenance requirements are relatively small. Any
imbalance of the rotor can lead to vibration, which in extreme cases can lead to a blade letting
al that the turbine be turned
liquid water content. If water gets
into the steam and is blasted on to the blades (moisture carryover, rapid impingement and
mbalance and catastrophic failure. Also, water
entering the blades this, 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,
23

29. 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 over speed 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. 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.
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30. The 210 MW Turbine of Thermal Power Project
Since I got specially assigned to the turbine department, I had the privilege of understanding
turbines more closely. Apart from the kind of turbine employed, its specifications, I came across
various concepts regarding the steam turbines like axial shift, casing expansion and learnt about
the same.
The turbine used for electricity generation is a three cylinder- reheat- condensing turbine. This
name means that the turbine assembly is made of three turbines, namely:-
1) HP turbine (high pressure turbine)
2) IP turbine (intermediate pressure turbine)
3) LP turbine (low pressure turbine)
The term reheat is used to imply that the steam, after passing the hp turbine and before
entering the ip turbine, is reheated by passing it through the boiler again.
Since the previous introduction we are well aware of the importance of a turbine and its
working in a power plant. There are various other aspects like axial shift, casing expansion,
bearings, turbine lubrication etc. Turbine requires perfect conditions to work efficiently. The
manufacturer of turbine is BHEL which is abbreviation of BHARAT HEAVY ELECTRICALS LTD. The
turbine is based on KWU design, Which stands for KRAFT WORKS UNION.
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31. The given manufacturer as specified certain condition for turbine working and certain
specification of the same, which are as follows.
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32. Construction
The turbine is a tandem compound machine which separates the hp, ip and lp 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 connects 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.
IP TURBINE
The ip turbine is a dual flow turbine, with horizontally split casings. This is to facilitate thermal
movement of inner casing within outer casing.
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 firtree
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 root
sand riveted shrouding. The last three stages of lp turbine have fabricated guide blades.
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33. 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. 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 babbit lining. The temperature of the bearing is measured in the two opposite
thrust pads on each side.
SHAFTSEALANFBLADETIPSEALING
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 clearances.
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 ip turbine has two reheat stop valves and control valves. The reheat stop valves are single
seat spring action valve, while the control valves are single seat valves loaded with diffusers.
The control valves operate in parallel and are completely open in the upper load range.
The main, reheat and control valves are supported free to move in thermal expansion. All the
valves are operated by individual hydraulic servomotors.
TURBINECONTROLSYSTEM
The turbine has an electro hydraulic control system backed up with hydraulic governing system.
An electric system measures the speed and output and controls them by operating the control
valves hydraulically via controller electro hydraulic converter. The electro hydraulic
controller ensure controlled acceleration of the turbine generator up to the rated speed and
prevents the over shooting of speed in case of sudden load rejections. The linear power
frequency droop characteristics can be adjusted in fine steps even when the turbine is running.
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34. TURBINEMONITORINGSYSTEM
In addition to measuring and display instruments for pressure, temperatures, valve lifts and
speed etc. the monitoring system also includes the instruments for measuring and indicating
the following parameters:-
•Absolute expansion measured at the front and rear bearing pedestal of the hp turbine.
•Differential expansion of hp and ip turbines.
•Rotor expansion measured at the rear bearing pedestal of the lp turbine.
•Axial shift measured at the hp-ip pedestal.
•Bearing pedestal vibration, measured at all turbine bearings.
•Shaft vibration measured at all turbine bearings.
Turbine Stress Controller is provided to monitor thermal stresses in vital turbine components.
OILSUPPLYSYSTEM
A single oil supply system lubricates and cool the bearings, governs the machine, operates the
hydraulic actuators and the safety and the protective devices and the drives the hydraulic
timing gear. The main oil pump is driven by turbine shaft and draws oil from main oil tank.
Auxiliary oil pumps maintain the oil supply on start-up and shut down, during turning gear
operation and when the main oil pump is faulted. When the turning is started a jacking oil
pump forces high pressure oil under the shaft journals the prevent boundary lubrication. The
lubricating and cooling oil is passed through oil coolers before entering the bearings.
AXIALSHIFT
The axial shift is the measure of axial displacement of the shaft within the thrust bearing. Axial
shift is set at zero when thrust is at the center of the axial clearance at the thrust pads. Axial
shift towards generator is positive and towards generator is negative. Alarm and tripping is
provided when the axial shift reading exceeds the set value.
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35. MARKETTING STRATEGIES
The UPRVUNL, is the sister organization of UPPCL, hence all of the electricity generated is sold
to UPPCL at a fixed rate which is decided by UP State Electricity Regulatory Authority. The other
by product, which is fly-ash, is sold to various cement factories like Diamond factory and
cement factory of Satna.
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36. Diversification or Expansion
The Parichha thermal power project is in a constant state of expansion in context to the
power produced. Earlier the plant was of the capacity of 110X2 MW only. Its power output was
increased to the capacity of 640MW by installation of 210X2 MW units. The development is not
stopped yet, there is installation 250X2 MW units underway and are expected to be operational
with in some time .Due to aggressive policy of government in power sector, the power sector is
going to show aggressive growth in the coming years.
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37. Suggestions
The plant is working fine with not many hindrances, but the main concern is the cleanliness
of plant. The plant, especially 110X2 units building of the plant is not clean enough. What I
believe is that cleaner environment might help in improving of productivity and decrease the
rate of break downs. This might improve the efficiency of the unit as lesser number of foreign
elements will be present which prevent the proper functioning of the unit. If the efficiency
increases, the coal consumption will be reduced for the same load and that would provide a
better profit to the organization.
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38. Conclusion
From all the study it can be concluded that the Pariccha thermal power project of 210X2 units is
a fairly 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
requirementsmay proves hazardous to the turbine.
Another interesting yet worrying fact is the quantity of coal consumed which
approximately10800 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
in reducing 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
awesme to see how all the components work in a synchronized manner.
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