it will definitely help you in your 3rd year training report

1. A
Summer Training Report
On
Study of Thermal Power Plant
At
“MEJIA THERMAL POWER STATION, DVC”
Submitted in partial fulfilment of the requirements for the
degree of
Bachelor of Technology in Mechanical Engineering
Submitted By
GROUP - 3
Roll No: 20, 23, 24 & 45
DEPARTMENT OF MECHANICAL ENGINEERING
HOOGHLY ENGINEERING & TECHNLOGY COLLEGE
VIVEKANANDA ROAD, PIPULPATI
P.O & DIST. HOOGHLY

2. GROUP MEMBERS
Name
 AKASH KUMAR GUPTA
 PRASANT LANG
 NITISH KUMAR KHALKHO
 NILESH PRASHANT LAKRA
Roll No.
 45
 20
 23
 24

3. CONTENTS
 Introduction
 Technical specification of MTPS
 Overview of Mejia Thermal Power Plant
 Power plant layout
 Working classification
A. Mechanical operation
B. Electrical operation
 Stepwise operation
 Other equipment's used in the
power plants
 Protection/safety devices

4. INTRODUCTION
 Thermal Power Station creates electrical energy by burning coal.
 Coal is burnt in a boiler which converts water into steam. The
expansion of steam in turbine produces mechanical power which
drives the alternator coupled to the turbine.
 Thermal Power Plants contribute maximum to the generation of
Power for any country . Thermal Power Plants constitute 75.43% of
the total installed captive and non-captive power generation in
India.
 In thermal generating stations coal, oil, natural gas etc. are
employed as primary sources of energy

5. TECHNICAL SPECIFICATION OF MTPS
Station Unit No. Capacity(MW) Boiler
Make
Turbine
Make
Mejia TPS
1,2,3 & 4 210 BHEL BHEL
5 & 6 250 BHEL BHEL
Mejia TPS
Ph-II
1 & 2 500 BHEL BHEL
INSTALLED CAPACITY: -
1) Total number of Units : - 4 X 210
MW(unit 1 to 4) with Brush Type
Generators, 2 X 250 MW(unit 5 and
6) with Brush less Type Generators,
2*500 MW(unit 7 and 8) Generators.
2) Total Energy Generation: - 2340 MW
3) Source of Water: - Damodar River
4) Sources of Coal: - B.C.C.L and E.C.L,
also imported from Indonesia

6. OVERVIEW OF THERMAL POWER PLANT
 Damodar Valley Corporation was established on 7th July 1948.
 The MTPS under the DVC is the second largest thermal plant in West
Bengal.
 It has the capacity of 2340 MW with 4 units of 210 MW each, 2 units of
250 MW each & 2 units of 500 MW each.
 With the introduction of another two units of 500 MW that is in
construction it will be the largest in West Bengal.
 Mejia Thermal Power Station is located in the outskirts of Raniganj in
Bankura District.
 The total power plant campus area is surrounded by boundary walls and is
basically divided into two major parts, first the Power Plant area itself and
the second is the Colony area for the residence and other facilities for
MTPSs ͛͛employees.

7. GENERAL LAYOUT OF THERMAL
POWER PLANT

8. WORKING CLASSIFICATION
(MECHANICAL OPERATION)
EQUIPMENT USED:
 Coal handling plant
 Water treatment plant
 DM plant
 Boiler
 Ash handling plant
 Electro-Static Precipitator
 Draft fans
 Pulverizing plant
 Turbine
 Condenser
 Cooling towers and ponds
 Economizer

9. COAL HANDLING PLANT
 The function of coal handling plant is
automatic feeding of coal to the boiler
furnace.
 A thermal power plant burns enormous
amounts of coal.
 A 200MW plant may require around 2000
tons of coal daily

10. WATER TREATMENT PLANT
Raw water supply:
Raw water received at the thermal power plant is
passed through Water Treatment Plant to separate
suspended impurities and dissolved gases
including organic substance and then through De-
mineralised Plant to separate soluble impurities.
Deaeration:
In this process, the raw water is sprayed over
cascade aerator in which water flows downwards
over many steps in the form of thin waterfalls.
Cascading increases surface area of water to
facilitate easy separation of dissolved undesirable
gases (like hydrogen sulphide, ammonia, volatile
organic compound etc.) or to help in oxygenation
of mainly ferrous ions in presence of atmospheric
oxygen to ferric ions. These ferric ions promote to
some extent in coagulation process.

11. WATER TREATMENT PLANT
Coagulation: Coagulation takes place in clariflocculator.
Coagulant destabilises suspended solids and agglomerates
them into heavier floc, which is separated out through
sedimentation. Prime chemicals used for coagulation are alum,
poly-aluminium chloride (PAC).
Filtration: Filters remove coarse suspended matter and
remaining floc or sludge after coagulation and also reduce the
chlorine demand of the water. Filter beds are developed by
placing gravel or coarse anthracite and sand in layers. These
filter beds are regenerated by backwashing and air blowing
through it.
Chlorination: Neutral organic matter is very heterogeneous i.e.
it contains many classes of high molecular weight organic
compounds. Humic substances constitute a major portion of
the dissolved organic carbon from surface waters. They are
complex mixtures of organic compounds with relatively
unknown structures and chemical composition.

12. DM(DE-MINERALISED WATER) PLANT
 In De-mineralised Plant, the filter water of Water Treatment Plant is passed
through the pressure sand filter (PSF) to reduce turbidity and then through
activated charcoal filter (ACF) to adsorb the residual chlorine and iron in filter
water.

13. BOILER
 Boiler is an enclosed vessel in which water is
heated and circulated until the water is turned
in to steam at the required pressure.
 Coal is burned inside the combustion chamber
of boiler. The products of combustion are
nothing but gases. These gases which are at
high temperature vaporize the water inside the
boiler to steam.
 Boilers are classified as:
1. Fire tube boilers
2. Water tube boilers
3. Superheater
4. Reheater

14. IMPORTANT PARTS OF BOILER
Important parts of the boiler
are:
 Steam drum
 Superheater & Re-heater
 Attemperator
 Air preheater
 Drain &
 Vent
 Economizer

15. ASH HANDLING PLANT
 The percentage of ash in coal is
5% in good quality coal & about
40% in poor quality coal.
 Power plants generally use poor
quality of coal , thus amount of
ash produced by it is quite large.
 A modern 1000MW plant
produces about 4800 tons of ash
daily.
 The stations use some conveyor
arrangement to carry ash to dump
sites.

16. ELECTRO-STATIC PRECIPITATOR
 Each boiler has 4 passes with 7 fields each
containing high voltage electrodes
 These attract the dust or ash from the flue
gases
 At regular intervals the electrodes are rapped
with motor-driven hammers and the PFA
falls into hoppers below
 In a year 1,000 MW station may generate 1.5
million ton of ash
 This is one of the ways to clean up the flue
gases or smoke sent up the chimney
 Secondly this ash is used by construction
industry for use in building materials (bricks
!!, Cement Fillers)

17. DRAFTS SYSTEM
 Circulation of air or gas is caused by difference in pressure known as
Draft.
 These fans are responsible for the flow of gasses through boiler.
 Forced Draft Fans used in the inlet of the boiler system.
 Induced Draft Fans used in the outlet of the boiler system.
 Mechanical efficiency =(AHP/BHP)*100
 Difference between AHP & BHP due to the Skin Friction, Turbulence,
Mechanical Friction, Leakage.
1. Erosion
2. Corosion
3. Vibration
are the mechanisms which are responsible for the damage & need serious
and costly maintenance.

18. PULVERIZING PLANT
 Pulverizing is a process of exposing a large surface
area to the action of oxygen and consequently
helping in combustion.
 Pulverized or powdered coal are highly inflammable.
 Pulverized Coal mixed with air and burned in the
fluid gas flow.
 Bio-mass and other materials can also be added to
the mixture.
 According to their working principle these mills are
classified as
1.CONTACT MILLS
2. BOWL MILL
3. IMPACT MILLS

19. TURBINE
 A steam turbine is a device that extracts thermal energy from pressurized steam
and uses it to do mechanical work on a rotating output shaft.
 The steam turbine is a form of
heat engine that derives much of
its improvement in
thermodynamic efficiency from
the use of multiple stages in the
expansion of the steam, which
results in a closer approach to the
ideal reversible expansion
process.

20. CONDENSER
 Steam after rotating steam turbine comes to
condenser. Condenser refers here to the shell and
tube heat exchanger (or surface condenser) installed
at the outlet of every steam turbine in Thermal
power stations of utility companies.
 Condenser used to condense the exhausted steam
from turbine to obtain maximum efficiency.
 The purpose is to condense the outlet (or exhaust)
steam from steam turbine to obtain maximum
efficiency and also to get the condensed steam in
the form of pure water, otherwise known as
condensate, back to steam generator or (boiler) as
boiler feed water.
 Condensers are classified as:
i)Jet condensers or contact condensers,
ii)Surface condensers.

21. COOLING TOWER
 The condensate (water) formed in the
condenser after condensation is initially at
high temperature. This hot water is passed
to cooling towers.
 It is a tower- or building-like device in which
atmospheric air (the heat receiver) circulates
in direct or indirect contact with warmer
water (the heat source) and the water is
thereby cooled.
 Types Of Cooling Tower-
1. Wet cooling tower
2. Dry cooling tower

22. ECONOMIZER
 Flue gases coming out of the boiler carry lot of
heat. Function of economizer is to recover some
of the heat from the heat carried away in the flue
gases up the chimney and utilize for heating the
feed water to the boiler.
 It is placed in the passage of flue gases in
between the exit from the boiler and the entry to
the chimney.
 The use of economizer results in saving in coal
consumption, increase in steaming rate and high
boiler efficiency but needs extra investment and
increase in maintenance costs and floor area
required for the plant.

23. WORKING CLASSIFICATION
(ELECTRICAL OPERATION)
EQUIPMENT USED:
 Electric Generator
 Automatic Voltage Generator
 Transformers
 Alternator
 Excitation System
 Switchyard Section

24. ELECTRICAL GENERATOR
In M.T.P.S. there are 6 electric generators for units 1 to 6. These are 3 phase turbo
generators, 2 pole cylindrical rotor type synchronous machines which are directly
coupled to the steam turbine. The generator consist of 2 parts mainly the stator and the
rotor.
Stator: The stator body is designed to withstand internal
pressure of hydrogen-air mixture without any residual
deformation. The stator core is built up of segmental
punching of high permeability, low loss CRGOS steel and are
in interleaved manner on spring core bars to reduce heating
and eddy current loss.
Rotor: Rotor is of cylindrical type shaft and body forged in
one piece from chromium nickel molybdenum and vanadium
steel. Slots are machined on the outer surface to incorporate
windings. Winding consists of coil made from hand drawn
silver copper with bonded insulation.
Turbogenerator

25. AUTOMATIC VOLTAGE
CONTROLLER(AVR)
 Heart of excitation system of the generator.
 Uses semiconductor elements to achieve high reliability with very fast response.
 Has two independent channels, the auto channel with close loop voltage regulation
and the manual channel with open loop regulation.

26. TRANSFORMER
 Transfers electric energy from 1 AC circuit to
one or more other circuits, either increasing
(stepping up) or reducing (stepping down)
the voltage
 In MTPS Phase-II there are 2 sets of
Generating Transformers(GT) (each set for
each Alternator unit). Each set comprises of 3-
single phase transformers connected as star in
output and delta at input.
 Each 1-phase 200MVA transforms 21KV to
400KV known as Generating Transformer(GT)
 Each Station Transformer(ST) transforms
incoming 400kv from switchyard to 11kv
 Further stepped down to 3.3KV by SAT and
415V by SST

27. ALTERNATOR
 Converts mechanical power into electrical form and feeds it into the power system
network. The working principle behind the operation of Alternator is Faraday’s law of
electromagnetic induction. The induced alternating voltage in a generator can be
expressed as-
E=4.44fTФ Volts
Where,
E=Voltage induced in volt.
f=frequency of rotation in Hz.
T=no. of turns.
Ф=flux per pole in Wb.
MECHANICAL
ENERGY
ELECTRICAL
ENERGY

28. EXCITATION SYSTEM
 The purpose of excitation system is to continuously
provide the appropriate amount of D.C field current
to the generator field winding.
 In MEJIA thermal plant for unit # 5,6,7,8 the
excitation is brushless but for #1, 2, 3, 4 the
excitation is brush excitation.
 The types of excitation system are
1. DC excitation
2. Static excitation
3. Brushless excitation.

29. SWITCHYARD SECTION
 Switchyard is an essential hub to co-ordinate
the exchange of power between the
generators & the transmission lines.
 In the MTPS there is a big 220 KV switchyard
for the unit 1 to 6.
 400 KV switchyard for the unit #7 & 8.
 It’s a junction point where the power coming
& going out to the external circuit.
 Junction point as deals with the large amount
of power, high capacity of conductors spread
throughout the section.
 It is necessary that it remains secure and
serviceable to supply the outgoing
transmission feeders. Circuit Diagram: 220kV switchyard of M.T.P.S

30. COMPONENTS OF SWITCHYARD
 Bus Bars
 Circuit Breakers
 Pre-Insertion Resistors
 Grading Capacitor
 Isolator
 Earth Switch
 Current Transformer (CT)
 Capacitive Voltage Transformer
(CVT)
 Lightning Arrester
 Wave Trap
 Battery Room
 Control Panel

31. Bus Bars
Circuit Breakers
Potential Transformer

32. STEPWISE OPERATION
1) First the pulverized coal is burnt into the furnace of boiler.
2) High pressure steam is produced in the boiler.
3) This steam is then passed through the super heater, where it further heated up.
4) This supper heated steam is then entered into a turbine at high speed.
5) In turbine this steam force rotates the turbine blades that means here in the turbine
the stored potential energy of the high pressured steam is converted into mechanical
energy.
6) After rotating the turbine blades, the steam has lost its high pressure, passes out of
turbine blades and enters into a condenser.
7) in the condenser the cold water is circulated with help of pump which condenses the
low pressure wet steam.
8) This condensed water is then further supplied to low pressure water heater where the
low pressure steam increases the temperature of this feed water; it is then again heated
in a high pressure heater where the high pressure of steam is used for heating.
9) The turbine in thermal power station acts as a prime mover of the alternator.

33. OTHER EQUIPMENT USED IN THE
POWER PLANTS
Electric motors: maximum motors used in the power
plant are 3-ph AC squirrel cage type like
• Service water pump
• Primary air fan
• Boiler feed pump
• Slurry Disposal pump
• Draft fans etc.
Synchro scope: before delivering power to the grid station
required to synchronize with the grid phase angles and
with the other parameters.
Control Panel: it’s a panel board from where the
engineers monitor the parameters.

34. PROTECTION/SAFETY DEVICES
Safety
equipment’s
used
By
the
engineers
and
workers