College minor project and report seminar for electrical engineering student on Thermal power plant. Project report on electricity generation in thermal power plant using coal.

1. Thermal Power Plant

2. Basic Layout

3. THERMAL POWER STATION
• 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(Alternator). After
it passes through the turbine, the steam is
condensed in a Condenser; this is known
as a Rankine cycle.

4. Rankine Cycle

5. Rankine Cycle
• There are four processes in the Rankine cycle, each changing
the state of the working fluid. These states are identified by
number in the diagram to the right.
• Process 1-2: The working fluid is pumped from low to high
pressure, as the fluid is a liquid at this stage the pump
requires little input energy.
• Process 2-3: The high pressure liquid enters a boiler where it
is heated at constant pressure by an external heat source to
become a dry saturated vapor.
• Process 3-4: The dry saturated vapor expands through a
turbine, generating power. This decreases the temperature
and pressure of the vapor, and some condensation may
occur.
• Process 4-1: The wet vapor then enters a condenser where it
is condensed at a constant pressure and temperature to
become a saturated liquid. The pressure and temperature of
the condenser is fixed by the temperature of the cooling coils
as the fluid is undergoing a phase-change.

6. What is a boiler?
• The steam generating Boiler is basically a
heat exchanger which has to produce
steam at the high purity, pressure and
temperature required for the steam turbine
that drives the electrical generator.

7. Boiler Parts
• The Boiler includes the Economizer, the steam
drum, the chemical dosing equipment, and the
furnace with its steam generating tubes and the
super heater coils. Necessary safety valves are
located at suitable points to avoid excessive
boiler pressure. The air and flue gas path
equipment include: forced draft (FD) fan, air
preheater (APH), boiler furnace, induced draft
(ID) fan, fly ash collectors (electrostatic
precipitator or baghouse) and the flue gas stack.

8. Air Pre-Heater (APH)
• APH is a heat exchanger in which air
temperature is raised by transferring
heat from other fluid such as flue
gases.

9. APH TYPES
1. Recuperative Type : Heating medium is on one side & air
is on the other side of tube /plate & heat transfer is by
conduction through the material which separates the
media.
2. Regenerative Type : Heating medium flows through a
closely packed rotating matrix to raise its temperature and
then air is passed through the matrix to take up the heat.

10. APH(TRISECTOR TYPE)
• Tri-sector types are the most common in modern power
generation facilities.In the tri-sector design, the largest sector
(usually spanning about half the cross-section of the casing) is
connected to the boiler hot gas outlet. The hot exhaust gas flows
over the central element, transferring some of its heat to the
element, and is then ducted away for further treatment in dust
collectors and other equipment before being expelled from the
flue gas stack. The second, smaller sector, is fed with ambient air
by a fan, which passes over the heated element as it rotates into
the sector, and is heated before being carried to the boiler
furnace for combustion. The third sector is the smallest one and
it heats air which is routed into the pulverizers and used to carry
the coal-air mixture to coal boiler burners. Thus, the total air
heated in the RAPH provides: heating air to remove the moisture
from the pulverised coal dust, carrier air for transporting the
pulverised coal to the boiler burners and the primary air for
combustion.

11. Boiler Draft Control
• Induced draft: This is obtained one of three ways, the first being the
"stack effect" of a heated chimney, in which the flue gas is less dense than
the ambient air surrounding the boiler. The denser column of ambient air
forces combustion air into and through the boiler. The second method is
through use of a steam jet. The steam jet oriented in the direction of flue
gas flow induces flue gasses into the stack and allows for a greater flue gas
velocity increasing the overall draft in the furnace. This method was
common on steam driven locomotives which could not have tall chimneys.
The third method is by simply using an induced draft fan (ID fan) which
removes flue gases from the furnace and forces the exhaust gas up the
stack. Almost all induced draft furnaces operate with a slightly negative
pressure.
• Forced draft: Draft is obtained by forcing air into the furnace by means
of a fan (FD fan) and ductwork. Air is often passed through an air heater;
which, as the name suggests, heats the air going into the furnace in order to
increase the overall efficiency of the boiler. Dampers are used to control the
quantity of air admitted to the furnace. Forced draft furnaces usually have a
positive pressure.
• Balanced draft: Balanced draft is obtained through use of both
induced and forced draft. This is more common with larger boilers where the
flue gases have to travel a long distance through many boiler passes. The
induced draft fan works in conjunction with the forced draft fan allowing the
furnace pressure to be maintained slightly below atmospheric

12. ESP
• An electrostatic precipitator is a large, industrial emission-control
unit. It is designed to trap and remove dust particles from the
exhaust gas stream of an industrial process.

13. Steam turbine
• A steam turbine is a mechanical device
that extracts thermal energy from
pressurized steam, and converts it into
rotary motion.
• Because the turbine generates rotary
motion, it is particularly suited to be used
to drive an electrical generator – about
80% of all electricity generation in the
world is by use of steam turbines.

14. Turbine Shaft

15. Principle of 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 .

16. Impulse Turbines
– An impulse turbine has 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
steam chest pressure to condenser pressure (or atmosphere
pressure). Due to this relatively 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 is 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".

17. Reaction Turbines
– 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.

18. Steam Condenser
• Surface condenser is the commonly used term for a
water cooled shell and tube heat exchanger installed on
the exhaust steam from a steam turbine in thermal
power stations. These condensers are heat exchangers
which convert steam from its gaseous to its liquid state
at a pressure below atmospheric pressure. Where
cooling water is in short supply, an air-cooled condenser
is often used. An air-cooled condenser is however
significantly more expensive and cannot achieve as low
a steam turbine exhaust pressure as a surface
condenser

19. Alternator
• An alternator is an electromechanical device that
converts mechanical energy to alternating current
electrical energy. Most alternators use a rotating
magnetic field but linear alternators are occasionally
used. In principle, any AC electrical generator can be
called an alternator, but usually the word refers to small
rotating machines driven by automotive and other
internal combustion engines

20. Principle of operation
• Alternators generate electricity by the same principle as DC generators,
namely, when the magnetic field around a conductor changes, a current is
induced in the conductor. Typically, a rotating magnet called the rotor turns
within a stationary set of conductors wound in coils on an iron core, called
the stator. The field cuts across the conductors, generating an electrical
current, as the mechanical input causes the rotor to turn.
• The rotating magnetic field induces an AC voltage in the stator windings.
Often there are three sets of stator windings, physically offset so that the
rotating magnetic field produces three phase currents, displaced by one-
third of a period with respect to each other.
• The rotor magnetic field may be produced by induction (in a "brushless"
alternator), by permanent magnets (in very small machines), or by a rotor
winding energized with direct current through slip rings and brushes. The
rotor magnetic field may even be provided by stationary field winding, with
moving poles in the rotor. Automotive alternators invariably use a rotor
winding, which allows control of the alternator generated voltage by varying
the current in the rotor field winding. Permanent magnet machines avoid the
loss due to magnetizing current in the rotor, but are restricted in size, owing
to the cost of the magnet material. Since the permanent magnet field is
constant, the terminal voltage varies directly with the speed of the
generator. Brushless AC generators are usually larger machines than those
used in automotive applications.and the large alternators in power station
which are driven by steam turbine are called turbo alternators

21. Poles verses RPM
• The output frequency of an
alternator depends on the
number of poles and the
rotational speed. The speed
corresponding to a particular
frequency is called the
synchronous speed for that
frequency. This table gives
some examples:
Poles RPM at
50Hz
2 3000
4 1500
6 1000
8 750
10 600
12 500
14 428.6
16 375
18 333.3
20 300

22. CLZS Parameters
• Captive Power Plant in Chanderiya consists of 3
units (2X77 MW + 1X80 MW).
• All three units are supplied by BHEL,
Hyderabad.
• While supplying uninterrupted and reliable
power to Chanderiya Lead Zinc Smelter, the
CPP has been additionally wheeling power to its
Agucha, Debari and Dariba units of Hindustan
Zinc Limited.
• Recently sale of power has also been initiated
with both RSEB and power exchange.

23. • In the Financial year 2008-’09,the 234 MW CPP the
operating parameters for U1,2,3 were PLF (100.2%,
93.4% and 95.0 % respectively), Availability
(98.5%,97.3% and 88.9% respectively), Auxiliary
consumption(8.93%,9.35% and 9.53% respectively.
• With a vision to reduce Cost of generation, usage of
Indian Coal has been increased.
• The Plant is actually designed for pulverized fuel with
coal imported from Indonesia and South Africa having
10% moisture,12% ash,55% fixed carbon,23% volatile
matter and 6000Kcal/Kg.
• In comparison to pure imported coal being used earlier,
blending of around 40 % Indian coal was started thereby
reducing the cost of coal significantly.

24. • Day-to-Day operational and maintenance
hurdles were faced as per an action plan and
overcome.
• Usage of linkage coal, which has a potential to
reduce coal cost by around Rs.1200/MT has
been started.
• Chanderiya CPP has upheld highest standard of
Environmental consciousness by discharging
minimum effluents, both gaseous and liquid, into
the atmosphere.
• The SPM, SOX, NOx and other gaseous
effluents have been maintained well below the
pre-defined norms set by the governing bodies.

25. AWARDS
• The Captive Power Plant of Hindustan Zinc Limited won Asian
Power Plant of the year and Best Emission reductions project in
Asia in the year 2006-07
• CPP, HZL was proud to receive awards in two categories from
the “Confederation of Indian Industry” at “National Competition
for Excellence in Water Management”. The Categories in which
CPP, HZL excelled were Innovative Case Study and Water
Efficient Unit.
• Operation and Maintenance of CPP has been outsourced to KPS
(Korea Plant Engineering & Services).
• KPS has deputed around 10 Korean persons who are stationed
in Chanderiya. They hold managerial positions of various
technical and non-technical departments.
• They have also recruited specialized/experienced Operation and
maintenance personnel who look after the operation and
maintenance part of the CPP.)

27. CPP CONTROL ROOM

28. OPERATIONAL BOILER PARAMETERS
1. Furnace Draft
2. Oxygen at APH inlet
3. Feed water flow
4. Steam flow
5. Air flow
6. Coal flow
7. Oil flow
8. Deaerator level
9. Drum level
10.MS Temperature
11.MS Pressure

29. BOILER TRIPPINGS
• Boiler trips on M. F. T.
• Drum level Very Low : -375mmwc
• Drum level Very high : -25mmwc
• Furnace draft very High : 150mmwc :
• Loss of I.D. Fans
• Loss of F. D. Fans
• Loss of P. A. Fans
• Furnace Slagging
• High Super-heater temperature : >540 deg. C
• Low super-heater temperature : 480 deg.C
• Ignitor fails to ignite
• Mill trip
• Flame instability : (Flame failure)
• Water wall tube failure
• Economizer Tube Failure
• Super-heater tube failure