CHAPTER –1
INTRODUCTION
For the power generation with 2x110 MW, 3x210 MW and
2X195 MW of K.S.T.P.S. authorities are required to be operative to active full
operation. The auxiliaries are basically
operation either on L.T. System i.e. 415 V 3-Ø power supply is made available
to the system after providing the station transformer of 3x50 MVA capacity with
voltage 220 KV/ 7.2/7.2 KV & different service transformers of capacity 1.0
MVA, 1.5 MVA, 2.0 MVA, which are located near the load centre as the transformer
having the voltage of 6.6 KV /415 V. The
6.6 KV power is distributed through 6.6 KV interconnected Bus System for all
the five units with a
control through DC of 220 V. The 415 V power supply is
done through a L.T. SWGR (Switchgear) which are located nearby the distribution
transformer as well as the load centers.
The all incomers, which are breaker controlled , are having the control
the L.T. SWGR are having the control system on 110/ 220 V AC. The 6.6 KV power supply which are either
MOCB (Minimum Oil Circuit Breaker) of or
Air Circuit Breakers.
The
6.6 KV power supply to various draining
equipment’s i.e. more is made through breakers which are either MOCB of
Jyoti make air circuit breaker which are either of voltage makers as well as SF
6 of NGEF make. The LT supply is also
controlled through air break circuit breaker which are either L&T make or
English Electric Company of India . The various H.T. motors are switched on
started through on direct ON line (DOL) in order to inverse the availability of
equipment at full efficiency without time gap.
CHAPTER
-2
GENERAL
LAYOUT & BASIC IDEA
A control system of station basically works on Rankin
Cycle. Steam is produced in Boiler is
exported in prime mover and is condensed in condenser to be fed into the boiler
again. In practice of good number of
modifications are affected so as to have heat economy and to increase the
thermal efficiency of plant\
The Kota Thermal Power Station is divided into four main circuits :
The Kota Thermal Power Station is divided into four main circuits :
Ø Fuel and Ash Circuit
Ø Air and Gas Circuit
Ø Feed water and Steam Circuit
Ø Cooling
Water Circuit
2.1
FUEL & ASH CIRCUIT:-
Fuel from the storage is fed to the boiler through fuel
handling device. The fuel used in KSTPS is coal, which on combustion in the
boiler produced the ash. The quantity of
ash produced is approximately 35-40% of coal used. This ash is collected at the back of the
boiler and removed to ash storage tank through ash disposal equipment.
2.2
AIR AND GAS CIRCUIT:-
Air from the atmosphere is supplied to the combustion
chamber of Boiler through the action of forced draft fan and induced draft
fan. The flue gas gases are first pass
around the boiler tubes and super heated tubes in the furnace, next through
dust collector (ESP) & then economizer.
Finally, they are exhausted to the atmosphere through fans.
COAL HANDLING PLANT
INTRODUCTION:-
It
can be called the heart of thermal power plant because it provided the fuel for
combustion in boiler. The coal is
brought to the KSTPS through rails there are fourteen tracks in all for
transportation of coal through rails.
The main coal sources for KSTPS are SECL (South Eastern Coalfields
Limited), NCL (Northern Coalfield Limited). Everyday 6 to 7 trains of coal are
unloaded at KSTPS. Each train consists
of 58 wagons and each wagon consists of 50 tones of coal. The approximate per
day consumption at KSTPS is about 18000 metric tones. It costs approximate 4.5 crores of rupees per
day including transportation expenses.
The coal is firstly unloaded from wagon by wagon triplers then crushed
by crushers and magnetic pulley and pulverized to be transformed to the
boiler. The whole transportation of coal
is through conveyor belt operated by 3-Ø Induction motor.
Main parts of granulator like break plates, cages
crushing rings and other internal parts are made of tough manganese (Mn) steel.
The rotor consists of four rows of crushing rings each set having 20 Nos. of
toothed rings and 18 Nos. of plain rings. In CHP Stage 1 & 2 having 64 Nos.
of ring hammers. These rows are hung on
a pair
of suspension shaft mounted on rotor discs. Crushers of this type employ
the centrifugal force of swinging rings stroking the coal to produce the
crushing action. The coal is admitted at
the top and the rings stroke the coal downward. The coal discharges through
grating at the bottom.
The coal handling plant can broadly be divided into three sections:-
1) Wagon Unloading System.
2) Crushing System.
3) Conveying System.
CHAPTER -3
BOILERS
A
boiler (or steam generator) is a closed vessel in which water, under pressure
is converted into steam. It is one of the major components of a thermal power
plant. A boiler is always designed to absorb maximum amount of heat released in
process of combustion. This is transferred to the boiler by all the three modes
of heat transfer i.e. conduction, convection and radiation.
3.1 BOILERS ARE CLASSIFIED AS:-
3.1.1Firetubeboiler:- In this type the products of
combustion pass through the tubes which are surrounded by water. These are
economical for low pressure only.
3.1.2 Water tube boiler:-
In this type of boiler water flows inside the tubes and
hot gases flow outside the tubes. These tubes are interconnected to common
water channels and to steam outlet.
Ø The
water tube boilers have many advantages over the fire tube boilers
Ø High
evaporation capacity due to availability of large heating surface.
Ø Better
heat transfer to the mass of water.
Ø Better
efficiency of plant owing to rapid and uniform circulation of water in tubes.
Ø Better
overall control.
Ø Easy
removal of scale from inside the tubes.
In KSTPS, Natural
circulation, tangentially fired, over hanged type, Water tube boilers are used.
Oil burners are provided between coal burners for initial start up and flame
stabilization. Firstly, light oil (diesel oil) is sprayed for initialization
then heavy oil (high speed diesel oil) is used for stabilization of flame. Pulverized coal is directly fed from the coal
mills to the burners at the four corners of the furnace through coal pipes with
the help of heated air coming from PA fan. Four nos. of ball mills of 34MT/hr.
capacity each have been installed for each boiler. The pressure inside boiler
is -ive so as to minimized the pollution and looses & to prevent the
accidents outside the boiler.
For ensuring safe operation of boilers, furnace safe
guard supervisory system (FSSS) of combustion engineering USA designed has been
installed. This equipment systematically feed fuel to furnace as per load requirement. The UV flame scanners installed in each of
the four corners of the furnace, scan the
flame conditions and in case of unsafe working conditions trip the boiler and
consequently the turbine. Turbine -
boiler interlocks safe guarding the boiler against possibility furnace
explosion owing to flame failure.
CHAPTER –
4
STEAM
TURBINE
Turbine is a machine in which a shaft is rotated
steadily by impact or reaction of current or stream of working substance (steam,
air, water, gases etc) upon blades of a wheel. It converts the potential or
kinetic energy of the working substance into mechanical power by virtue of
dynamic action of working substance.
When the working substance is steam it is called the steam turbine.
4.1
PRINCIPAL OF OPERATION OF STEAM TURBINE:-
Ø Working
of the steam turbine depends wholly upon the dynamic action of Steam. The steam is caused to fall in pressure in a
passage of nozzle: doe to this fall in pressure a certain amount of heat energy
is converted into mechanical kinetic energy and the steam is set moving with a
greater velocity. The rapidly moving
particles of steam, enter the moving part of the turbine and here suffer a change
in direction of motion which gives rose to change of momentum and therefore to
a force. This constitutes the driving
force of the machine. The processor of
expansion and direction changing may occur once or a number of times in
succession and may be carried out with difference of detail. The passage of steam through moving part of
the commonly called the blade, may take place in such a manner that the
pressure at the outlet side of the blade is equal to that at the inlet
inside. Such a turbine is broadly termed
as impulse
turbine. On the other hand the pressure of the steam at outlet from the moving
CHAPTER – 5
EXCITATION
SYSTEMS:-
The electric power Generators requires direct
current excited magnets for its field system.
The excitation system must be reliable, stable in operation and must
response quickly to excitation current requirements. When excitation system response is controlled
by fast acting regulators, it is chiefly dependent on exciter. Exciter supply is given from transformer and
then rectified.
5.1 STATIC EXCITATION SYSTEM:-
In KSTPS static excitation system is provided it mainly consists of the following:-
Ø Rectifier
transformer
Ø Nos.
of thyristor converters
Ø An
automatic voltage regulator (AVR)
Ø Field
suppression equipment
Ø Field
flashing equipment
CHAPTER -7
PROTECTIONS
Ø Field
Protection
Ø Pole
Slipping
Ø Plane
Overload Protection
Ø Inter-turn
Fault
Ø Negative
Phase Sequence Protection
Ø Reverse
Power Protection
Ø Forward
Power Protection
Ø Under
Frequency & Over Frequency Protection
Ø Generator
Voltage Protection
Ø Rotor
Earth Fault Protection
7.1 GENERAL
PROTECTION:
It is most important electrical equipment of many
generating station. Tripping of even a generating unit may cause overloading of
associated machines and
even to system un-stability. The basis function of protection applied to
generator is to reduce voltage to minimum by rapid discrimination clearance of
faults. Unlike other apparatus the
opening of C.B. to isolate faulty generator is not sufficient to prevent future
damage.
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