The document provides an overview of the components and operation of a thermal power plant. It discusses the key elements including coal handling, pulverizers, boilers, superheaters, turbines, generators, condensers and cooling towers. The coal is pulverized and burned to produce steam, which spins turbines connected to generators to produce electricity. The steam is then condensed and recycled to the boilers to complete the Rankine cycle. The document outlines the functions of the major equipment in a coal-fired thermal power station.

1. INDUSTRIAL VISIT REPORT
OF
THERMAL POWER STATION
by
DEPARTMENT OF ELECTRICAL ENGINEERING
SISTec Ratibad Campus

2. INDEX
 Abstract
 Introduction
 what is thermal powerplant
 Schematic of thermal powerplant
 Different elements of powerstation
 Coal Preparation
 Fans
 Boiler
 Superheater
 Turbine
 Generator
 Condenser
 Cooling Tower
 Boiler Feed Pump
 Ash Handling plant
 Thermal power plant operation
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3. Introduction
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Whatis Thermal power Plant
A thermal power station is a power plant in which heat energy is
converted to electric power. In most of the places in the world the turbine 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 heat sources, fossil fuel dominates
here, although nuclear heat energy and solar heat energy are also used.
Some prefer to use the term energy centre because such facilities convert
forms of heat energy into electrical energy. Certain thermal power plants
also are designed to produce heat energy for industrial purposes of district
heating, or desalination of water, in addition to generating electrical power.
Types of Thermal Energy
Almost all coal, nuclear, geothermal, solar thermal electric, and waste
incineration plants, as well as many natural gas power plants are thermal.
Natural gas is frequently combusted in gas turbines as well as boilers. The
waste heat from a gas turbine, in the form of hot exhaust gas, can be used to
raise steam, by passing this gas through a Heat Recovery Steam Generator
(HRSG) the steam is then used to drive a steam turbine in a combined cycle
plant that improves overall efficiency. Power plants burning coal, fuel oil, or
natural gas are often called fossil-fuel power plants. Some biomass- fueled
thermal power plants have appeared also. Non-nuclear thermal power
plants, particularly fossil-fueled plants, which do not use co-generation are

4. sometimes referred to as conventional power plants.
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5. Commercial electric utility power stations are usually constructed on a large
scale and designed for continuous operation. Virtually all Electric power plants
use three-phase electrical generators to produce alternating current (AC)
electric power at a frequency of 50 Hz. Large companies or institutions may
have their own power plants to supply heating or electricity to their facilities,
especially if steam is created anyway for other purposes. Steam-driven
power plants have been used to drive most ships in most of the 20th century
until recently. Steam power plants are now only used in large nuclear naval
ships. Shipboard power plants usually directly couple the turbine to the
ship's propellers through gearboxes. Power plants in such ships also provide
steam to smaller turbines driving electric generators to supply electricity.
Nuclear marine propulsion is, with few exceptions, used only in naval
vessels. There have been many turbo-electric ships in which a steam- driven
turbine drives an electric generator which powers an electric motor for
propulsion.
Combined heat and power plants (CH&P plants), often called co-generation
plants, produce both electric power and heat for process heat or space heating.
Steam and hot water.
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6. Diagram of a typical coal-fired thermal power station
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7. Thermal Power Plant
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.
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.

8. Introductory overview
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 andcrushed
to a size of 20mm. From the crusher house the coal is either stored in dead
storage( generally 40 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 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 super
heater 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.
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9. Principal
Coal based thermal power plant works on the principalof Modified Rankine
Cycle.
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10. Components of Coal Fired Thermal Power Station:
 Coal Preparation
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Fig. Coal Handling Plant
i)Fuel preparation system: Incoal-firedpower 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, so that coal will undergo complete
combustion during combustion process.

11. pulverizer is a mechanical device for the grinding of many different types of
materials. For example, they are used to pulverize coal for combustion in the
steam-generating furnaces of fossil fuel power plants Types of Pulverisers: Ball
and Tube mills; Ring and Ball mills; MPS; Ball mill; Demolition.
ii)Dryers: they are used in order to remove the excess moisture from coal
mainly wetted during transport. As the presence of moisture will result in fall
in efficiency due to incomplete combustion and alsoresult in CO emission
iii)Magneticseparators:coal which is brought may contain iron particles.
These iron particles may result in wear and tear. The iron particles may
include bolts, nuts wire fish plates etc. so these are unwanted and so are
removed with the help of magnetic separators.
The coal we finally get after these above process are transferred to the storage
site.
Purpose of fuel storage is two –
 Fuel storage is insurance fromfailureof normal operating supplies to
arrive.
 Storage permits some choice of the date of purchase, allowing the
purchaserto take advantage of seasonal market conditions. Storage of
coal is primarily a matter of protection against the coal strikes, failure
of the transportation system & general coal shortages.
 Fan
In a boiler it is essential to supply a controlled amount of air to the furnace for
Effective combustion of fuel and to evacuate hot gases formed in thefurnace
through the various heat transfer area of the boiler. This can be done by using
a chimney or mechanical device such as fans which acts as pump
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12.  Natural fans
When the required flow of air and flue gas through a boiler can be obtained
by the stack (chimney) alone, the system is called natural draught. When the
gas within the stack is hot, its specific weight will be less than the cool air
outside; therefore the unit pressure at the base of stack resulting from weight
of the column of hot gas within the stack will be less than the column of
extreme cool air. The difference in the pressure will cause a flow of gas
through opening in base of stack. Also the chimney is form of nozzle, so the
pressure at top is very small and gases flow from high pressure to low pressure
at the top.
i) Mechanized fans
There are 3 types of mechanized draught systems
1) Forced draught fans
2) Induced draught fans
3) Balanced draught fans
 Forced Draught Fan:-In this system a fan called Forced draught fan is
installed at the inlet of the boiler. This fan forces the atmospheric air through
the boiler furnace and pushes out the hot gases from the furnace through
superheater, reheater, economiser and air heater to stacks.
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13. Forceddraughtfan:–
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Fig. FD Fan
Induced draught fan : – Here a fan called ID fan is provided at the outlet of
boiler, that is, just before the chimney. This fan sucks hot gases from the
furnace through the superheaters, economiser, reheater and discharges gas
into the chimney. This results in the furnace pressure lower than atmosphere
and affects the flow of air from outside to the furnace.

14. Fig. ID Fan
Primary Draught fan:-In this systemboth FD fan and ID fan are provided. The
FD fan is utilized to draw control quantity of air from atmosphere and force
the same into furnace. The ID fan sucks the product of combustion from
furnace and discharges into chimney. The point where draught is zero is
called balancing point.
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15. There are two types of storage:
1. Live Storage (boiler room storage): storage from which coal may be
withdrawn to supply combustion equipment with little or no remanding
is live storage. This storage consists of about 24 to 30 hrs. of coal
requirements of the plant and is usually a covered storage in the plant
near the boiler furnace. The live storage can be provided with bunkers &
coal bins. Bunkers are enough capacity to store the requisite of coal.
From bunkers coal is transferred to the boiler grates.
2. Dead storage- stored for future use. Mainly it is for longer period of time,
and it is also mandatory to keep a backup of fuel for specified amount of
days depending on the reputation of the company and itsconnectivity.
There are many forms of storage some of which are –
1. Stacking the coal in heaps over availableopen ground areas.
2. As in (I). But placed under cover or alternatively in bunkers.
3. Allocating special areas & surrounding these with high reinforced
concerted retakingwalls.
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16. Boiler and auxiliaries
Fig. Boiler
A Boiler or steam generator essentially is a container into which water can
be fed and steam can be taken out at desired pressure, temperature and flow.
This calls for application of heat on the container.
have a facility to burn a fuel and release the heat. The functions of a boiler
thus can be stated as:-
1. To convert chemical energy of the fuel into heat energy
2. To transfer this heat energy to water for evaporation as well to steam for
superheating.
The basic components of Boiler are: -
1. Furnace and Burners
2. Steam and Superheating
a. Low temperature super heater
b. Platen super heater
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17. c. Final super heater
Types Of Boiler
.
Fire-tube Boilers
Fig. Fire tube Boiler
In fire-tube boilers, combustiongases pass throughthe insideof the tubes with
water surrounding the outside of the tubes. The advantages of a fire-tube
boiler are its simple constructionand less rigid water treatment requirements.
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18. The disadvantages are the excessive weight-per-pound of steam generated,
excessive time required to raise steam pressure because of the relatively large
volume of water, and inability to respond quickly to load changes, again, due
to the large water volume.
The most common fire-tubeboilers used in facility heating applications are
often referred to as ''scotch'' or''scotch marine'' boilers, as this boiler type was
commonly used for marine service because of its compact size (fire-box
integral with boiler section)
.
Water tube Boiler
Fig. Water tube Boiler
in a water-tube boiler ('''Figure 3'''), the water is inside the tubes and
combustion gases pass around the outside of the tubes. The advantages of a
water-tube boiler are a lower unit weight-per-pound of steam generated, less
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19. time required to raise steam pressure, a greater flexibility for responding to
load changes, and a greater ability to operate at high rates of steam generation.
A water-tube design is the exact opposite of a fire-tube. Here, the water flows
throughthe tubes and is encased in a furnace in which the burner fires. These
tubes are connected to a steam drum and a mud drum. The water is heated
and steam is produced in the upper drum.
 Economiser

Fig. Economiser
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20. It is located below the LPSH in the boiler and above pre heater. It is there to
improve the efficiency of boiler by extracting heat from flue gases to heat
water and send it to boiler drum.
Advantages of Economiser include
1)Fuel economy: – used to save fuel and increase overall efficiency of boiler
plant.
2)Reducing size of boiler: – as the feed water is preheated in the economiser
and enter boiler tube at elevated temperature. The heat transfer area required
for evaporation reduced considerably.
 Air Preheater
The heat carried out with the flue gases coming out of economiser are further
utilized for preheating the air before supplying to the combustion chamber. It
is a necessary equipment for supply of hot air for drying the coal in pulverized
fuel systems to facilitate grinding and satisfactory combustion of fuel in the
furnace
 Superheater
Fig. Superheater
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.
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21. When a steam system is designed for superheat, the designershould ensure
that the steamexit thesuperheateris superheated about 5.6oC(10oC) higherthan
the desired superheat temperature. The steam temperature is not controlled
using bypasses on the superheaters but by desuperheating equipment.
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22. Types of Turbine
 Steam turbines
Fig. Steam Turbine
Steam turbines have been used predominantly as prime mover in all thermal
power stations. The steam turbines are mainly divided into two groups: -
1. Impulse turbine
2. Impulse-reaction turbine
The turbine generator consists of a series of steam turbines interconnected to
each other and a generator on a common shaft. There is a high pressure
turbine at one end, followed by an intermediate pressure turbine, two low
pressure turbines, and the generator. The steam at high temperature (536 ‘c to
540 ‘c) and pressure (140 to 170 kg/cm2) is expanded in the turbine.
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23.  Water Turbine
Fig. Water Turbine
A water turbine is a rotary machine that converts kinetic energy and
potential energy of water into mechanical work.
Water turbines were developed in the 19th century and were widely used for
industrial power prior to electrical grids. Now they are mostly used for electric
power generation. Water turbines are mostly found in dams to generate
electric power from water kinetic energy.
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24.  Wind Turbine
Fig. Wind Turbine
A wind turbine is a device that converts the wind's kinetic
energy into electrical power. Wind turbines are manufactured in a wide
range of vertical and horizontal axis types. The smallest turbines are
used for applications suchas battery charging for auxiliary power for
boats or caravans or to power traffic warning signs. Slightly larger
turbines can be used for making contributions to a domestic power
supply while selling unused power back to the utility supplier via
the electrical grid. Arrays of large turbines, known as wind farms, are
becoming an increasinglyimportant source of intermittent renewable
energy and are used by many countries as part of a strategy to reduce
their reliance on fossil fuels.
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25.  Generator
Fig. Generator
Generator or Alternator is the electrical end of a turbo-generator set. It is
generally known as the piece of equipment that converts the mechanical
energy of turbine into electricity. The generation of electricity is based on the
principle of electromagnetic induction.
In electricity generation, a generator is a device that converts mechanical
energy to electrical energy for use in an external circuit. Sources of
mechanical energy include steam turbines, gas turbines, water turbines, and
internal combustion engines and even hand cranks. The first electromagnetic
generator, the Faraday disk, was built in 1831 by British scientist Michael
Faraday. Generators provide nearly all of the power for electric power grids.
The reverse conversion of electrical energy into mechanical energy is done by
an electric motor, and motors and generators have many similarities. Many
motors can be mechanically driven to generate electricity and frequently make
acceptable manual generators.
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26.  Condenser
Fig. Condenser
The condenser condenses the steam from the exhaust of the turbine into
liquid to allow it to be pumped. If the condenser can be made cooler, the
pressure of the exhaust steam is reduced and efficiency of the cycle
increases. The functions of a condenser are:-
1) To provide lowest economic heat rejection temperature for steam.
2)To convert exhaust steam to water for reserve thus saving on feed water
requirement.
3) To introduce make up water.
We normally use surface condenser although there is one direct contact
condenser as well. In direct contact type exhaust steam is mixed with directly
with D.M cooling water.
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27. Cooling
tower
Fig. Cooling Tower
The cooling tower is a semi-enclosed device for evaporative cooling
of water by contact with air. The hot water coming out from the condenser is
fed to the tower on the top and allowed to tickle in form of thin sheets or
drops. The air flows from bottom of the tower or perpendicular to the
direction of water flow and then exhausts to the atmosphere after effective
cooling.
The cooling towers are of four types: -
1. Natural Draft cooling tower
2. Forced Draft cooling tower
3. Induced Draft cooling tower
4. Balanced Draft cooling tower
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28.  Boiler feed pump
Fig. Boiler Feed pump
Boiler feed pump is a multi stage pump provided for pumping feed
water to economiser. BFP is the biggest auxiliary equipment after Boiler and
Turbine. It consumes about 4 to 5 % of total electricity generation.
Boiler feed water pump is a specific type of pump used to pump
feed water into a steam boiler. The water may be freshly supplied or
returning condensate produced as a result of the condensation of the steam
produced by the boiler. These pumps are normally high pressure units that
take suction from a condensate return system and can be of the centrifugal
pump type or positive displacement type.
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29.  Ash handling system
Fig. Ash Handling Plant
The disposal of ash from a large capacity power station is of same
importance as ash is produced in large quantities. Ash handling is a major
problem.
i)Manual handling : While barrows are used for this. The ash is collected
directly through the ash outlet door from the boiler into the container from
manually.
ii)Mechanical handling : Mechanical equipment is used for ash disposal,
mainly bucket elevator, belt conveyer. Ash generated is 20% in the form of
bottom ash and next 80% through flue gases, so called Fly ash and collected in
ESP.
iii)Electrostatic precipitator : From air preheater this flue gases (mixed with
ash) goes to ESP. The precipitator has plate banks (A-F) which are insulated
from each other between which the flue gases are made to pass. The dust
particles are ionized and attracted by charged electrodes. The electrodes are
maintained at 60KV.Hammering is done to the plates so that fly ash comes down
and collect at the bottom. The fly ash is dry form is used in cement manufacture.
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30. Advantages of coal based thermal Power Plant
 They can respond to rapidly changing loads without difficulty
 A portion of the steam generated can be used as a process steam in
different industries
 Steam engines and turbines can work under 25 % of overload
continuously
 Fuel used is cheaper
 Cheaper in production cost in comparison with that of diesel power
stations
Disadvantages of coal based thermal Power Plant
 Maintenance and operating costs are high
 Long time required for erection and putting into action
 A large quantity of water is required
 Great difficulty experienced in coal handling
 Presence of troubles due to smoke and heat in the plant
 Unavailability of good quality coal
 Maximum of heat energy lost
 Problem of ash removing
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31. Thermal Power Plants Operation
Thermal power plants use water as working fluid. Nuclear and coal based
power plants fall under this category. The way energy from fuel gets
transformed into electricityforms the working of a power plant. In a thermal
power plant a steam turbine is rotated with help of high pressure and high
temperature steam and this rotation is transferred to a generator to produce
electricity.
Fig.1 Power is produced in thermal power plants by rotating steam turbine
Energy absorption from steam
When turbine blades get rotated by high pressure high temperature steam, the
steam loses its energy. This in turn will result in a low pressure and low
temperature steam at the outlet of the turbine. Here steam is expanded till
saturationpoint is reached. Since there is no heat addition or removal from the
steam, ideally entropy of the steam remains same. This change is depicted in
the following p-v and T-s diagrams. If we can bring this low pressure, low
temperature steam back to its original state, then we can produce electricity
continuously.
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32. Fig.2 Pressure and temperature drop of steam when turbine absorbs energy from it
Use of Condenser
Compressing a fluid which is in gaseous state requires a huge amount of
energy,so before compressing the fluid it should be converted into liquid state.
A condenser is used for this purpose, which rejects heat to the surrounding
and converts steam into liquid. Ideally there will not be any pressure change
during this heat rejection process, since the fluid is free to expand in a
condenser. Changes in fluid are shown in the p-v and T-s diagram below.
Fig.3 Use of condenser in order to transform vapor into liquid state
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33. Pump
At exit of the condenser fluid is in liquid state, so we can use a pump to raise
the pressure.During this process the volume and temperature (2 -3 deg.C
rise)of fluid hardly changes, since it is in liquid state. Now the fluid has
regained its original pressure.
Fig.4 Compressor pumps the fluid to its original pressure
Heat Addition in Boiler & Rankine Cycle
Here external heat is added to the fluid in order to bring fluid back to its
original temperature. This heat is added through a heat exchanger called a
boiler. Here the pressure of the fluid remains the same, since it is free to
expand in heat exchanger tubes. Temperature rises and liquid gets
transformed to vapor and regains its original temperature. This completes the
thermodynamic cycle of a thermal power plant, called Rankine Cycle. This
cycle can be repeated and continuous power production is possible.
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34. Fig.5 Heat addition at boiler brings the fluid to its original temperature
Condenser Heat Rejection - Cooling Tower
In order to reject heat from the condenser a colder liquid should make contact
with it. In a thermal power plant continuous supply of cold liquid is produced
with the help of a cooling tower. Cold fluid from the cooling tower absorbs
heat from a condenser and gets heated, this heat is rejected to the atmosphere
via natural convection with the help of a cooling tower.
Boiler furnace for Heat Addition
Heat is added to the boiler with help of a boiler furnace. Here fuel reacts with
air and produces heat. In a thermal power plant, the fuel can be either coal or
nuclear. When coal is used as a fuel it produces a lot of pollutants which have
to be removed before ejecting to the surroundings. This is done using a series
of steps, the most important of them is an electro static precipitator (ESP)
which removes ash particles from the exhaust. Now much cleaner exhaust is
ejected into the atmosphere via a stack.
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35. Fig.6 Main accessories of Rankine cycle - Cooling tower, Boiler furnace, ESP & Chimney
Optimizing a Thermal plant performance
There are various flow parameters which have to be fine-tuned in order to get
optimum performance from a thermal power plant.Lowering the condenser
temperature or raising the average boiler temperature will result in a high
efficiency power plant cycle according to the 2nd law of thermodynamics
(Carnot efficiency),most of the performance improving technologies are
working on this idea. Some latest trends are listed below.
1. Expanding TurbineAfterSaturation
Expanding the steam in the turbine even after reaching the saturation point
may be a dangerous affair. As the steam goes below saturation, wetness of
the steam increases. These condensed water droplets collide with the
turbine blades rotating at a high speed, thus it can cause extreme tip
erosion to the blades. Turbine blade tip erosion is shown in figure below.
But as you expand more you will be able to absorb more energy from the
steam, thus increasing power plant efficiency. Up to 15% wetness level is
considered to be safe for steam turbine operation. So most of the steam
turbine will expand up to this point in order to extract maximum energy
from the fluid. This is shown in figure below.
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36. Fig.7 Expanding turbine below saturation point in order to gain maximum power from steam
2. Raising average boiler temperature
If you can increase the average heat addition temperature of the boiler, that
will result in a power plant with higher efficiency. One way to do this is to
increase the compressor pressure. This will shift the saturation point of the
fluid to a higher level, thus providing higher average temperature of heat
addition. This is shown in the figure below. The blue line represents change
in the cycle after raising the compressor pressure.
Fig.8 Raising compressor pressure in order achieve higher average boiler temperature
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37. Sagarinstituteof scienceTechnolgy& Research,RatibadCampus
The student of Sagar institute of science Technolgy &
Research,Ratibad campus had gone for an industrial visit to Thermal Power
Station and had learned about the power generation. Such industrial visit help
the student in understanding the practical application side of the course.
DEPARTMENTOF ELECTRICALENGINEERING
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38. OUR EXPERIENCE FROM THE INDUSTRIAL VISIT:
After completing the industrial visit, we have upgraded our knowledge at a
very great level. It was a good learning experience. In each and every
department, we got some or the other new ideas and new thinking which was
necessary for development.
ThankYou
VISITED ACULTY PROFILE:
1. Prof. Prasant Kumar
2. Prof. Aditya Prakash
3. Prof. Subinoy Roy
4. Prof. Kavita Kuswah
5. Mr. Arunendra Sachan
Prepared By:-
Mr.Prasant Kumar
AP,Department of electrical engineering
SISTec Ratibad Bhopal
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