Report on Vocational Training at Mejia Thermal Power Station
1. A REPORT OF THE
VOCATIONAL TRAINING
MEJIA THERMAL POWER STATION
By
Bappaditya Maity
MCKV INSTITUTE OF ENGINEERING
119/08/2016
2. INTRODUCTION
Damodar Valley Corporation was established on 7th July 1948.It is the most reputed company in the eastern zone of
India. DVC in established on the Damodar River. It also consists of the Durgapur Thermal Power Plant in Durgapur.
The MTPS under the DVC is the second largest thermal plant in West Bengal. It has the capacity of 2340MW with 4
units of 210MW each, 2 units of 250MW each & 2 units of 500 MW each. With the introduction of another two units
of 500MW that is in construction it will be the largest in West Bengal. Mejia Thermal Power Station also known as
MTPS is located in the outskirts of Raniganj in Bankura District. It is one of the 5 Thermal Power Stations of Damodar
Valley Corporation in the state of West Bengal.
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3. TECHNICAL SPECIFICATION OF MTPS:
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
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5. STEAM TURBINE
A steam turbine is a prime mover which continuously converts the energy of high pressure, high temperature steam supplied by
the boiler into shaft work with low pressure, low temperature steam exhausted to a condenser
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6. BOILER SYSTEM
BOILER:
Working principle of Boiler (Steam Generator): In Boiler, steam is generated from de- mineralized
water by the addition of heat.
The heat added has two parts: sensible heat and latent heat. The sensible heat raises the
temperature and pressure of water as well as steam. The latent heat converts water into steam
(phase change). This conversion is also known as boiling of water, which is dependent on pressure
and corresponding temperature.
Thermodynamically, boiling is a process of heat addition to water at constant pressure &
temperature.
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7. COAL HANDLING PLANT
Generally most of the thermal power plants uses low grades bituminous coal. The conveyer belt system transports the coal from
the coal storage area to the coal mill. Now the FHP(Fuel Handling Plant) department is responsible for converting the coal
converting it into fine granular dust by grinding process. The coal from the coal bunkers.Coal is the principal energy source
because of its large deposits and availability. Coal can be recovered from different mining techniques like
• shallow seams by removing the over burnt expose the coal seam
• underground mining.
The coal handling plant is used to store, transport and distribute coal which comes from the mine. The coal is delivered either
through a conveyor belt system or by rail or road transport. The bulk storage of coal at the power station is important for the
continues supply of fuel. Usually the stockpiles are divided into three main categories.
• live storage
• emergency storage
• long term compacted stockpile
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8. 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 atmospheri oxygen to ferric
ions. These ferric ions promote to some extent in coagulation process.
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9. DM (Demineralised 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.
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10. Induced draft fan (ID fan):
Induced draft represents the system where air or products of combustion are
driven out after combustion at boiler furnace by maintaining them at a progressively increasing sub atmospheric pressure. This
is achieved with the help of induced draft fan and stack. Induced draft fan is forward curved centrifugal (radial) fan and sucks
the fly-ash laden gas of temperature around 125°C out of the furnace to throw it into stack (chimney). The fan is connected
with driving motor through hydro-coupling or with variable frequency drive (VFD) motor to keep desired fan speed.
Forced draft fan (FD fan):
Forced draft represents flow of air or products of combustion at a pressure above atmosphere. The air for combustion is carried
under forced draft conditions and the fan used for this purpose is called Forced Draft (FD) fan. It is axial type fan and
is used to take air from atmosphere at ambient temperature to supply air for combustion, which takes entry to boiler through wind
box. In all units except Durgapur TPS Unit #4, this fan also supplies hot /cold air to the coal mills. The output of fan is controlled
by inlet vane / blade pitch control system.
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11. Cooling tower
Cooling towers cool the warm water discharged from the condenser and feed the cooled water back to the condenser. They
thus reduce the cooling water demand in the power plants. Wet cooling towers could be mechanically draught or natural
draught. In M.T.P.S the cooling towers are I.D. type for units 1-6 and natural draught for units 7&8.
CHIMNEY
•The chimney is 275 meters' high and 50,000 tonnes of reinforced concrete were used to make it
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12. ELECTRICALOPERATION
The electrical operation of a power plant comprises of generation, transmission and distribution of electrical energy. In a power
station both distribution and transmission operation can take place. When power is sent from power station to all other power
station in the grid, it is known as distribution of power. When power plant is driving power from other power station it is known
as transmission of power/electrical energy.
ELECTRIC 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.
Rating of the turbo generator
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Rated kW capacity 210000 kW
Rated kVA capacity 247000 kVA
Rated terminal voltage 15750 V
Rated power factor 0.85 lag
Rated stator current 9050 amps
Rated speed 3000 RPM
Rated frequency 50 Hz
Efficiency at rated power
output & power factor
98.55%
Power factor short circuit ratio 0.49
13. TRANSFORMERS
The electricity thus produced by the generator
then goes to the generating transformer where
the voltage is increased for transmission of
electricity with minimized copper losses.
Generating transformer#1 to 4
MVA: 150/200/250 (H.V.) MVA: 150/200/250 (L.V.)
Volts at no load: 240000 (H.V.) Volts at no load: 15750 (L.V.)
Ampere line value: 361/482/602 (H.V.)
Ampere line value: 5505/7340/9175 (L.V.) Phase-3 frequency:
50 Hz.
Mass of core and windings: 139000 kg.
Mass of oil: 38070 kg. Mass of heaviest package: 164000 kg.
Connection: YNd1 connection.
Generating transformer#5 and 6
MVA: 189/252/315 (H.V.) MVA: 189/252/315 (L.V.)
Volts at no load: 16.5kV (L.V.) Volts at no load: 240kV (H.V.)
Ampere line value: 757.57 (H.V.)
Ampere line value: 11022.14 (L.V.) Phase-3 frequency: 50 Hz.
Mass of core and windings: 155000 kg.
Mass of oil: 53070 kg. Mass of heaviest package: 18000 kg. 13
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14. The basic components of a switchyard are as follows:
1.Circuit breaker: A circuit breaker is an equipment that
breaks a circuit either manually or automatically under all
conditions at no load, full load or short circuit. Oil circuit
breakers, vacuum circuit breakers and SF6 circuit breakers are a
few types of circuit breakers.
2.Isolator: Isolators are switches which isolate the circuit at
times and thus serve the purpose of protection during off load
operation.
3.Current Transformer: These transformers used serve
the
purpose of protection and metering.
Generallythe same transformer can be
used as a current or potential transformer
depending on the type of connection with
the main circuit that is series or parallel
respectively.
In electrical system it is necessary to
a)Read current and power factor
b)Meter power consumption.
c)Detect abnormalities and feed impulse to protectivedevices.
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15. 5.POWER TRANSFORMER:
The use of power transformer in
a switchyard is to change the
voltage level. At the sending and
usually step up transformers are
used to evacuate power at
transmission voltage level. On
the other hand at the receiving
end step down transformers are
installed to match the voltage
to sub transmission or
distribution level. In many
switchyards autotransformers
are used widely for
interconnecting two switchyards
with different voltage level
(such as 132 and 220 KV)
33/11 KV Power Transformer in a switchyard 1519/08/2016
16. CONCLUSION
The practical experience that I have gathered during the overview training of large thermal power plant having a large
capacity of 2340 MW for Unit# I to VIII in three weeks will be very useful as a stepping stone in building bright
professional career in future life. It gave me large spectrum to utilize the theoretical knowledge and to put it into
practice. The trouble shooting activities in operation and decision making in case of crisis made me more confident to
work in the industrial atmosphere.
Moreover, this overview training has also given a self realization & hands-on experience in developing the personality,
interpersonal relationship with the professional executives, staffs and to develop the leadership ability in industry
dealing with workers of all categories.
I would like to thank everybody who has been a part of this project, without
whom this project would never be completed with such ease.
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