2. About NTPC
• 10th largest power generator in
the world, 3rd largest in asia.
• Total capacity = 43108 MW.
• Largest power company in India.
Contributes 25.6% power with
only 16% installed capacity.
• Vision: To be one of the world’s
largest and best power
utilities,powering India's growth.
• Mission:“Develop and provide
reliable power, related products
and services at competitive prices,
integrating multiple energy
sources with innovative and eco-
friendly technologies and
contribute to society.”
3. • 17 coal-based, 7 gas-based stations
• NTPC Badarpur: coal based power plant
• Installed capacity = 705 MW.
• 5 units. Units 1,2,3 = (3X95=285 MW) Units 4,5 = (210X2=420 MW)
• Power suplied via the Northern Grid, primarily via 10 transmission
lines: Sarita Vihar, Okhla, Mehrauli, Noida, Alwar, Ballabhgarh.
• Raw materials: Coal, water.
– Coal : Jharia coal fields in Jharkhand.
– Water : Agra canal.
• Water-highly impure-processed in Water Treatment Plant.
• Coal goes through coal cycle.
4. WATER TREATMENT PLANT
• Water is first checked for suspended impurities, organic matter in
clariflocculator.
-Suspended impurities: removed with potash alum
-Organic matter: removed by adding Cl2.
layers of activated charcoal
- Impurities removed by adsorption
resins rich in H+, OH- ions
- Salts removed from water.
Degaser : removes gases present in water.
5. • Water- again passed through
resins.
• Now, we get demineralized
water.
• Demineralized water: checked
if it meets requirements of
boiler.
6. Various Cycles In Thermal Power
Plant
• COAL CYCLE:
• Coal : brought in wagons
• Wagon tipplers: invert wagons, empty coal into hoppers, 22 m below
ground.
• Conveyors: take coal to crusher house.
• Magnetic Chamber: separates magnetic impurities from coal.
• Crusher House: 30 m above ground. Coal crushed to 50 mm size.
• Raw coal bunker: Holds coal in it.
7. • Raw coal feeder: supplies coal to mills
• Mills : 6 mills at NTPC. A,B,C,D,E,F.
• Furnace: Combustion of coal.
8. • Steam Cycle:
• Water: converted to steam in furnace.
• Boiler drum
• 14 superheaters : remove moisture from steam
• HP Turbine : steam expands, temperature, pressure reduce
• Reheaters : reheat water to 540 degree celsius.
• IP turbine
• LP turbine
• Condensor : at bottom of LP turbine.
9. • Condensate Cycle:
• Inside condensor, steam condenses to hot water.
• Condensate Extraction Pump
• LP Heaters 1A, 1B
• Gland Steam Cooler with ejector
• LP Heaters 2,3,4
• Deaerator : Removes gases (mainly Oxygen) from water.
• Boiler Feed Pump : Increases pressure of water.
10. • Feed Water Cycle:
• Boiler Feed Pump
• HP Heaters 5,6,7
• Economiser
• Boiler drum : through furnace via tubes
• Once again, the steam cycle takes place.
• Feed water is called so because as we see, condensed steam in
condenser is once again fed to turbine via furnace.
• Therefore, steam cycle, condensate cycle, feed water cycle
constitute a closed loop cycle.
11. • Flue gas cycle:
• Flue gases are formed in the funace, as a result of combustion.
• Platen Superheater
• Re heater
• Final and low temperature super heaters
• Economiser
• Air pre heater
• ESP : Removes ash present in Flue gases
• ID Fan
• Chimney
13. MEASUREMENT TECHNIQUES
• TEMPERATURE:
• THERMOCOUPLE:
• Consists of two dissimilar
conductors that contact each
other at one or more spots. It
produces a voltage when the
temperature of one of the spots
differs from the reference
temperature at other parts of
the circuit.
• Types of thermocoules:
– Type J
– Type K
– Type E
– Type T
– Type N
– Type S
– Type R
– Type B
14. • RESISTANCE
TEMPERATURE DETECTOR
(RTD):
• Based on the principle that a
material's resistance changes
with temperature.
• Main trend for industrial
resistance temperature
detector is platinum RTD due
to physical stability and high
applicable temperature.
• There are the other RTDs such
as Nickel, Platinum-cobalt, and
so on.
15. • Types of RTDs:
– Based on wiring configurations:
• TWO WIRE
• THREE WIRE
• FOUR WIRE
– Standard platinum Resistance Thermometers (SPRTs): Has highest
accuracy
– Secondary Standard platinum Resistance Thermometers (Secondary
SPRTs)
– Industrial PRTs : are designed to withstand industrial environments
16. • THERMOCOUPLES VS RTDs:
• Thermocouple vs. RTD:
• Temperature range:
• First, consider the difference in temperature ranges. Noble Metal Thermocouples can reach 3,100 F, while
standard RTDs have a limit of 600 F and extended range RTDs have a limit of 1,100 F.
• Cost:
• A plain stem thermocouple is 2 to 3 times less expensive than a plain stem RTD. A thermocouple head
assembly is roughly 50% less expensive than an equivalent RTD head assembly.
• Accuracy, Linearity, & Stability:
• As a general rule, RTDs are more accurate than thermocouples. This is especially true at lower
temperature ranges. RTDs are also more stable and have better linearity than thermocouples. If accuracy,
linearity, and stability are your primary concerns and your application is within an RTD’s temperature
limits, go with the RTD.
• Durability:
• In the sensors industry, RTDs are widely regarded as a less durable sensor when compared to
thermocouples.
• Response Time:
• RTDs cannot be grounded. For this reason, they have a slower response time than grounded
thermocouples. Also, thermocouples can be placed inside a smaller diameter sheath than RTDs. A
smaller sheath diameter will increase response time. For example, a grounded thermocouple inside a 1/16”
dia. sheath will have a faster response time than a RTD inside a ¼” dia. sheath.
17. • Pressure Measurement:
• Pressure measurement at NTPC
Badarpur is done mainly using
pressure sensors. Pressure
sensors are basically transducers:
they generate an output voltage
as a function of an input pressure.
• Types of pressure maesurements:
– Head pressure:Head pressure(or
pressure head) measures the static
pressure of a liquid in a tank or a
pipe. Head pressure, P, is a function
solely on the height of the liquid, h,
and weight density, w, of the liquid
being measured
18. • Absolute pressure
measurement is measured
relative to a vacuum
• Gauge pressure is measured
relative to ambient
atmospheric pressure
• Differential pressure is similar
to gauge pressure, but instead
of measuring relative to
ambient atmospheric pressure,
differential measurements are
taken with respect to a specific
reference pressure
19. • At NTPC Badarpur, the force collector type of sensor is used, where
a diaphragm measures the applied force per unit area.
• Many other kinds of pressure sensors.
– Wheatstone bridge (strain based) sensors :are the most common
– A variable capacitance pressure transducer: measures the change in
capacitance between a metal diaphragm and a fixed metal plate.
(Capacitance changes with change in distance between plates)
– Piezoelectric pressure transducer take advantage of the electrical
properties of naturally occurring crystals such as quartz. These crystals
generate an electrical charge when they are strained.
The natural output of a pressure transducer is a voltage.Many pressure
transducers will output a conditioned 0-5V signal or 4-20 mA current.
The 0-5V and 4-20 mA signals can easily be measured by Data Acquisition
(DAQ) hardware.
20. • FLOW MEASUREMENT:
• A flow sensor is a device for sensing the rate of fluid flow. Typically
a flow sensor is the sensing element used in a flow meter, or flow
logger, to record the flow of fluids
• the flow rate is determined inferentially by measuring the liquid's
velocity or the change in kinetic energy. Velocity depends on the
pressure differential that is forcing the liquid through a pipe or
conduit.
• The use of differential pressure as an inferred measurement of a
liquid's rate of flow is well known.
• This method exploits Bernoulli's theorem.
– P0 + hpg + (1/2)pv2 = constant , P0 = PRESSURE, p=DENSITY
OF FLUID
21. CONTROL OF VARIOUS PROCESSES
• Transmitters : Produce an output current of 4-20 mA, using 24V DC
input.
• 71E Card: Detects if current through transmitter less than 4 mA.
• 19E Card: Converts 4-20 mA current to 1-5 V voltage.
• 76R Card: setter card: Helps us set required voltage.
• 74R Card: error between measured, set value determined using PID
controller.
• Auto Manual Logic Card: connected to 4 switches: Manual, Auto,
Raise, Lower
• In auto mode, pins 6,26 of AML card connect to pins 7,27 respectively
22. • Pulse Collector Card: Collects any fasle pulses (basically noise).
• POS Cards: Switches which activate contactors.
23. HOW CIRCUITS ARE
CONTROLLED/ACTIVATED??
• Relays:
• Relays are simple switches which
are operated both electrically and
mechanically. Relays consist of a n
electromagnet and also a set of
contacts. The switching mechanism
is carried out with the help of the
electromagnet
• Iron core is surrounded by a control
coil. As shown, the power source is
given to the electromagnet through
a control switch and through
contacts to the load. When current
starts flowing through the control
coil, the electromagnet starts
energizing and thus intensifies the
magnetic field. Thus the upper
contact arm starts to be attracted to
the lower fixed arm and thus closes
the contacts causing a short circuit
for the power to the load.
24. • TYPES OF RELAYS:
• Normally Open Contact (NO) – NO contact is also called a make
contact. It closes the circuit when the relay is activated. It
disconnects the circuit when the relay is inactive.
• Normally Closed Contact (NC) – NC contact is also known as break
contact. This is opposite to the NO contact. When the relay is
activated, the circuit disconnects. When the relay is deactivated, the
circuit connects.
25. • As soon as the coil current is
off, the movable armature will
be returned by a force back to
its initial position.
• Shown left is a simple relay.
• When current is applied to coil,
it is magnetized, and the
switch closes.
• As soon as the current flow
stops through pins 1 and 3, the
switch opens and thus the
open circuit prevents the
current flow through pins 2 and
4. Thus the relay becomes de-
energized and thus in off
position.
26. TURBINE SUPERVISORY
INSTRUMENTATION
• Monitors. under all operating conditions, a multitude of turbine
generator operating parameters. These parameters are:
• Turbine generator bearing vibrations.
• HP and LP turbine axial differential expansions.
• Rotor Eccentricity
• Shaft axial position.
• . Information provided by the system is used by the control room
operator to verify that the turbine generator is operating within the
safe limits. And, if this is not the case, the operator should
takeappropriate actions to protect the machine from abnormal
conditions that could result in damage.
