akash ranjan
TRANSCRIPT
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GITAM UNIVERSITY
GITAM INSTITUTE OF TECHNOLOGY
DEPARTMENT OF ELECTRONICS & INSTRUMENTATION ENGINEERING
INDUSTRIAL TRAINING REPORT
NTPC DADRI POWER PLANT
STUDENT :
AKASH RANJAN
1210608102
TRAINING PLACE
NAME : NTPC DADRI (NATION CAPITAL POWER STATION )
ADDRESS : NTPC-Dadri,Vidyut Nagar-201008,Dist.Gautambudhnagar,UP
TRAINING DATE: Starting 01/06/2011 Completion: 30/06/2011
PHONE NO: 2671284
WEB ADDRESS: www.ntpc.co.in
Name & Designation Name & Designation Name & Designation
External Supervisor Internal Supervisor Coordinator, Industrial Training
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STUDENT DECLARATION
I hereby declare that this industrial training report titled NTPC DADRI POWER PLANT in
NTPC is executed as per the course requirement for the under graduate program in
engineering. It have not been submitted by me or any other person to any other university
or institution for degree or diploma. Its my own work.
Place:
Date:
AKASH RANJAN
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Department of Electronics & Instrumentation Engineering
GITAM UniversityVisakhapatnam - 530045
CERTIFICATE
This is to certify that Mr. AKASH RANJAN of B. Tech
(Electronics & Instrumentation Engineering) Roll No. 1210608102
has completed/ partially completed/ not completed his Industrial Training
during the acedemic year 2010-2011 as the partial fulfilment of the B.tech course.
Signature Signature
Name & Designation Name & Designation
Internal Supervisor Coordinator, Industrial Training
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ACKNOWLEDGEMENT
With profound respect and gratitude, I take the opportunity to convey my thanks to
complete the training here. I express gratitude to the Program Manager and other faculty
members of Electronics & Instrumentation Engineering og GITAM Institute of Technology
for providing this opportunity to undergo industrial training at National Thermal Power
Corporation, Dadri, New Delhi.
I do extend my heartfelt thanks to Ms. C. S. M. Burlawarfor providing me this opportunity
to be a part of this esteemed organization.
I am extremely grateful to Mrs.Rashmi Mathur, Senior Engineer, C & I Department at
NTPC Dadri Gas Plant, Dadri for his guidance during whole training.
I am extremely grateful to all the technical staff of NTPC DADRI GAS PLANT for their
co-operation and guidance that helped me a lot during the course of training. I have learnt a
lot working under them and I will always be indebted of them for this value addition in me.
Finally, I am indebted to all whosoever have contributed in this report work and friendly
stay at Nationsl Capital Power Station, Dadri, UP.
AKASH RANJAN
1210608102
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Contents
1. Introduction2. About NTPC
2.1Overview of NTPC
2.2Dadri Station-At a glance
3. Thermal Plant3.1 Thermal Power Generation
3.2 Coal Based Power Station
3.3By Products of Power Generation3.4Equipments in Thermal Plant
4. Control & Instrumentation Department4.1 Measurements in Power Plant
4.2 Control Room
4.3Temperature Measurement
4.4 FSSS Logic System
4.5 Pressure Measurement
4.6 Turbine Protection
5. Safety Measures of Thermal Power Plant6. Gas Plant
6.1 Introduction to Gas Power Plants
6.2 Salient Features of Gas Power Plant
6.3 Gas Plant Operation
6.4 Combined Cycle Power Plant
6.5 Heat Recovery Steam Generator
6.6 Steam Turbine
6.7 Transmission of Generated Power Onto the Grid
6.8 Water Tanks, Natural Gas Pipeline, Control Room
7. Technical Documentation
8. Conclusion
9. References
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1. INTRODUCTION
In present time we are seeing that industrial training is necessary for every technical &
management student. NTPC organize training programs according to the trade of trainee andsection of interest of the trainee. NTPC Dadri is the only national capital power station to
have both gas and coal based power generation capacity. It also has the capability to run both
the units simultaneously.
This report is based on my industrial visit to NTPC Power Plant at Dadri. Through this
report, I intend to give a detail about NTPC Dadri power plant and its operation. In this
modern era, every area of work say airport, railway, industries, military, shopping malls &
even domestic needs depends completely upon power supply. These area needs continuous
supply for there operation, therefore there is a need of a unit that can provide continuous
power supply to large sections of society.
NTPC has its core values as:
B BUSINESS ETHICS
C CONSUMER FOCUS
O ORGANISATION AND PROFESSIONAL
M MUTUAL RESPECT AND TRUST
I INNOVATION AND SPEED
T TOTAL QUALITY FOR EXCELLENCE
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2. About NTPC2.1Overview Of NTPC
NTPC was set up in the central sector in the 1975 in response to widening demand & supply
gap with the main objective of planning, promoting & organizing an integrated development
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to thermal power in India. Ever since its inception, NTPC has never looked back and the
corporation is treading steps of success one after the other. The only PSU to have achieved
excellent rating in respect of MOU targets signed with Govt. of India each year. NTPC is
poised to become a 40,000 MW giant corporation by the end of XI plan i.e. 2012 AD.
Lighting up one fourth of the nation, NTPC has an installed capacity of 29,394 MW from its
commitment to provide quality power; all the operating stations of NTPC located in the
National Capital Region & western have acquired ISO 9002 certification. The service
groups like Engineering, Contracts, materials and operation Services have also bagged the
ISO 9001 certification. NTPC Dadri, Ramagundam, Vindhyachal and Korba station have
also bagged ISO 14001 certification.
Today NTPC contributes more than 3 / 5th of the total power generation in India. As per
Forbes global 2000 ranking for the year 2005, NTPC was 463rd
biggest company in the
world and 5th biggest Indian company
As per ADBs memorandum NTPC is 2nd
largest Asian power generator.
2.2Dadri Station At a GlanceNTPC Dadri is model project of NTPC. Also it is the best project of NTPC also known as
NCPS (National capital power station). Situated 60 km away from Delhi in the District of
Gautama Budh Nagar, Uttar Pradesh. NTPCs Dadri plant is the only one in India to house
gas-based as well as coal-based generating units. The station has an installed capacity of
1669 MW of power840 MW from Coal based units and 829 MW Gas Based Station. The
coal-based stations boiler can be fired using 100% furnace oil as well.
NTPC Dadri has a total installed capacity of 1669.78 Mega Watts. The coal plant has 4 units
which were commissioned one by one from 1991 to 1994 .Each unit has a generation
capacity of 210 MW.
The Gas plant has 6 units which have a combined capacity of 829.78 MW. It has 4 gas
turbine units which were commissioned in 1992 while the 2 steam turbine units were
commissioned in 1994. The gas turbine units have a capacity of 130.19 MW each while the
steam turbines have a capacity of 154.51 MW each. The station has ~1,130 employees, who
have been given accommodation in an integrated township adjacent. The plant is spread over
2,665 acres, making it one of the largest sites in India.
The coal unit receives coal from North Karanpura mines located in Jharkhand, almost
1,400km from Dadri. The coal (grade E, calorific value ~4,324-5,089 Kcal/kg) is fed through
a rail link. NTPC has a dedicated railway siding that connects Dadri station and the plant.
Gas for the plant is supplied by GAIL and is sourced through the HBJ pipeline. The plant
consumes 4.7m tones of coal annually, and requires 4.0 mmsmd gases. However, owing to
the shortage of gas in India, actual supplies are only 2.5-2.6mmsmcd. Hence, although the
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coal plants PLF has been well over 90% since FY05, the gas stations PLF has been much
lower, at ~74% for the same period.
The station has the largest switchyard in India, with power-handling capacity of 4,500MW.
The station is excelling in performance ever since its commercial operation. It isconsistently in receipts of meritorious project awards, the coal based units of the station
stood first in the country in terms of PLF for the financial year 1999 2000 by
generating an all time national high PLF of 96.12 % with the most modern O & M
Practices. NTPC Dadri is committed to generating clean and green Power. The Station
also houses the first HVDC station of the country (GEP project) in association with centre
for power efficiency and Environment protection (CENEEP) NTPC & USAUID. The
station has bagged ISO 14001 & ISO 9002 certification during the financial year 1999
2000, certified by Agency of International repute M/s DNV Netherlands M/s DNV
Germany respectively.
As a part of the infrastructure for the Commonwealth Games, the station is adding coal-based
capacity of 980MW (Stage II expansion) consisting of two units of 490MW each.
3. Thermal Plant
Thermal power plants convert the heat of heat energy into electric energy, a variety of auxiliary
equipments are needed. The auxiliary equipments in a thermal plant are so much that they
overshadow the main equipments.
The coal handling plant supplies coal to the boiler. The ash formed in the boiler is disposed by
the ash handling plant. Air taken from the atmosphere by the action of force induced or draft
fan is heated in the preheater before being fed to the boiler. The flue gases pass through dust
collector, air preheater and economizer before being discharged to the atmosphere through the
energy of coal into electrical energy. Coal is burnt in a boiler which converts water into steam.
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The expansion of steam in turbine produces mechanical power which drives the alternator. To
achieve efficient conversion chimney. The boiler vaporizes water into steam; steam is further
heated in the super heater and fed to the high pressure turbine. After expanding in high pressure
turbine, steam is heated again in a boiler and fed to the low pressure turbine. The exhaust steam
from the low pressure turbine is condensed by the condenser and the condensate, along with
makeup water, is passed through economizer before being fed to the boiler
The coal plant produces a total power of 840MW. The coal-based stations boiler can be fired
using 100% furnace oil as well. The gas station has two modules, each consisting of four
130.2MW gas turbines, with a waste-heat recovery boiler and two 154.5MW steam turbines.
The station has the largest switchyard in India, with power-handling capacity of 4,500MW. As
a part of the infrastructure for the Commonwealth Games, the station is adding coal-based
capacity of 980MW (Stage II expansion) consisting of two units of 490MW each. The Dadri
plant is 50km away from Delhi, in the state of Uttar Pradesh. Road connectivity to the plant has
improved of late, thanks in large part to NTPCs efforts Dadri coal plant has the highest PLFs
among all of NTPCs units . The coal unit receives coal from North Karanpura mines located in
Jharkhand, almost 1,400km from Dadri. The coal (grade E, calorific value ~ 4,324-5,089
Kcal/kg) is fed through a rail link. NTPC has a dedicated railway siding that connects Dadri
station and the plant. Gas for the plant is supplied by GAIL and is sourced through the HBJ
pipeline. The plant consumes 4.7m tones of coal annually, and requires 4.0mmsmd gas.
However, owing to the shortage of gas in India, actual supplies are only 2.5-2.6mmsmcd. Hence,
although the coal plants PLF has been well over 90% since FY05, the gas stations PLF has
been much lower, at ~ 74% for the same period. Environment-friendly unit. The plant operates
the countrys largest fly-ash disposal facility, with 53m m3 storage capacity. Additionally,
Ambuja and Grasim have announced plans to set up cement units near the plant, to use the fly-
ash generated from the plant. As an incentive, NTPC will supply fly-ash to these plants free of
cost for the first few months. The thermal station currently produces 1.5m tones of fly-ash daily
and some of this is sold in auctions by NTPCs subsidiary NTPC Vidyut Vyapar Nigam. This
generates an additional ~ Rs350m income for NTPC annually. The unsold ash has been used to
create a flourishing nature park around the plant. The 550-acre ash mound acts as an ecosystem
for both flora and fauna. However, churn is evident at the corporate level, where such amenities
are not provided and the operating structure is more bureaucratic.
Dadri is a benchmark for the best operation practices .Dadri has adopted the best practices for
safety, environment protection and maintenance. This is evident from its ISO 9001-2000, ISO
14001 and OSAS 18001 certifications. Additionally, to improve infrastructure around the plant,
the company is laying a cement access road. 35% of material used would be fly-ash generated
by the plant. The Rs250m-300m expenditure incurred would be capitalized by NTPC. As a part
of supply-chain management, the station also assists coals mines in their operations and
maintenance. Dadri can add a further 500MW capacity through Brownfield expansion. The
existing campus has enough land available to allow an additional Brownfield expansion by
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500MW. Even for the Stage II expansion, only 200 acres additional land for the reservoir was
required.
3.1. Thermal Power Generation
In a conventional thermal power station, a fuel is used to heat water, which gives off steam athigh pressure. This in turn drives turbines to create electricity. At the heart of power stations is a
generator, a rotating machine that converts mechanical energy into electrical energy by creating
relative motion between a magnetic field and a conductor. The energy source harnessed to turn
the generator varies widely. It depends chiefly on which fuels are easily available and on the
types of technology used.
Thermal power plants are classified by the type of fuel used
Nuclear power plants use a nuclear reactors heat to operate a steam turbine generator Fossil fuelled power plants may also use a steam turbine generator or in the case of
natural gas fired plants may use a combustion turbine.
Geothermal power plants use steam extracted from hot underground rocks Renewable energy plants may be fuelled by waste from sugar cane, municipal solid
waste, landfill methane, or other forms of biomass
In integrated steel mills, blast furnace exhaust gas is a low-cost, although low-energy-density, fuel
Waste heat from industrial processes is occasionally concentrated enough to use forpower generation, usually in a steam boiler and turbine
Solar thermal electric plants use sunlight to boil water, which turns the generator3.2. Coal Based Power Stations
When coal is used for electricity generation, it is usually pulverised and then burned in a furnace
with a boiler. The furnace heat converts boiler water to steam, which is then used to spin
turbines which turn generators and create electricity.
The thermodynamic efficiency of this process has been improved over time. Standard steam
turbines have topped out with some of the most advanced reaching about 35% thermodynamic
efficiency for the entire process, which means 65% of the coal energy is waste heat released into
the surrounding environment. Old coal power plants, especially grandfathered plants, are
significantly less efficient and produce higher levels of waste heat. About 40% of the world's
electricity comes from coal.
3.3 By Products of Power Generation
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Byproducts of power plant operation need to be considered in both the design and operation.
Waste heat due to the finite efficiency of the power cycle must be released to the atmosphere,
often using a cooling tower, or river or lake water as a cooling medium. The fuel gas from
combustion of the fossil fuels is discharged to the air; this contains carbon dioxide and water
vapor, as well as other substances such as nitrogen, nitrous oxides, sulfur oxides, and (in the
case of coal-fired plants) fly ash and mercury. Solid waste ash from coal-fired boilers is
removed. Ash generated can be re-used for building materials.
3.4 Equipments in Thermal Plant
3.4.1Coal Handling Plant
The function of coal handling plant is automatic feeding of coal to the boiler furnace. A
grate at the bottom of the furnace holds the fuel bed. Coal is weighed and led to a hopperthrough a conveyer mechanism. From the hopper it is fed to the gate through some form of
stoker mechanism. The stoker may be an overfeed stoker or underfeed stoker depending on
whether coal entry is above or below the air entry. It require around 8,400 tons of coal daily.
In NTPC there is enough storage of coal to last for 15 days or so.
3.4.2 Pulverizing Plant
In modern thermal power plants, coal is pulverized i.e. ground to dust like and carried to the
furnace in a stream of hot air. Pulverization is a means of exposing a large surface area to
the action of oxygen and consequently helping the combustion.
ADVANTAGES
1. The rate of combustion can be controlled and changed quickly to meet the varying load.
2. The banking losses are reduced.
3. The percentage of excess air required is low.
4. Automatic combustion control can be used.
5. A wide variety of even low grade coals can be used.
6. The boiler can be started from cold conditions very rapidly.
DISADVANTAGES
1. Investment cost of plant is increased.
2. Explosion hazards exist. Therefore, skilled personnel are required.
3. Auxiliary power consumption of the plant is increased.
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4. A lot of extra equipments, mills, burners are needed.
3.4.3 Draft System
The combustion in the boiler requires a supply of sufficient quantity of air and removal of
exhaust gases.
The circulation of air is caused by a difference in pressure, known as draft. Thus draft is the
differential in pressure between the two points i.e. Atmosphere and inside the boiler. A
differential in draft is needed to cause flow of gases through the boiler setting. This required
differential is proportional to square of the rate of flow. It may be natural or mechanical.
NATURAL DRAFT
A natural draft is provided by a chimney or stack. Chimney serves two purposes i.e. it
produces a draft so that can flow into the boiler and products of combustion are discharged
to the atmosphere and it delivers the product of combustion and fly ash to a high altitude so
that air pollution is reduced. The gases within the chimney are at higher temperature than
that of the surrounding air.
MECHANICAL DRAFT
Modern large size plants use very huge size boilers of capacity above 1000,000 kg per
hour. Such boilers need tremendous volume of air. A chimney cannot provide enough draft
for this amount of air. Therefore mechanical draft is necessary. Of course a chimney is
always provided.
3.4.4. Boiler
A boiler 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 the process of combustion. This heat is transferred to
the boiler by all the three modes of heat transfer i.e. conduction, convection and radiation.
They are classified as fire tube boiler and water tube boiler.
FIRE TUBE BOILER
This boiler is so named because the product of the combustion passes through the tubes
which are surrounded by the water. Depending upon whether the tubes are horizontal or
vertical, they are further classified as horizontal or vertical tube boilers. They may be
internally fed or externally fed.
WATER TUBE BOILER
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In this boiler, water flows inside the tubes and hot gases flow outside the tubes .The tubes
are interconnected to common water channels and to steam outlet. Water tube boilers are
classified as vertical, horizontal and inclined tubes depending upon whether the tubes are
vertical, horizontal or inclined. The number of drums may be one or more.
3.4.5. Steam Turbine
A steam turbine converts heat energy of steam into mechanical energy and drives the
generator. It uses the principle that a steam when issuing from a small opening attains a high
velocity. This velocity attained during expansion depends on the initial and final heat
content represents the heat energy converted to kinetic energy. They are of two types
impulse and reaction turbine.
3.4.6. Ash Handling Plant
Coal contains a considerable amount of ash. The percentage of ash in the coal varies fromabout 5% in good quality coal to about 40% of poor quality coal. Power plants generally use
average or poor quality coal .As a result of this the ash produced by a plant is pretty large. A
modern 2000 MW plant produces 5000 tons of ash daily. Of this about 25% is furnace
bottom ash and remaining 75% is pulverized fuel ash or dust or fly ash .The small stations
use some conveyer arrangement to carry ash to dump sites directly or for carrying and
loading it to trucks and wagons which transport it to the site of disposal.. Large stations use
more elaborate arrangements and separate systems for the furnace bottom or fly ash.
3.4.7. Condenser
Condenser does the job of condensing the steam exhausted from turbine. Thus it helps in
maintaining low pressure at the exhaust, thereby permitting expansion of steam in the
turbine to a very low pressure. This improves the plant efficiency .The exhaust steam is
condensed and used as feed water to the boiler. Maintenance of high vacuum in the
condenser is essential for efficient operation. Any leakage of air in the condenser is essential
for efficient operation. Any leakage of air into the condenser destroys the vacuum. As it is
impossible to eliminate air leakage completely, a vacuum pump is necessary to remove the
air leaking into condenser.
3.4.8. Cooling Towers
The condenser needs huge quantity of water to condense the steam. Roughly one kg of
steam needs 100 kg of cooling water for the condenser. Such large requirement of water can
be met if the plant is situated by the side of a big river with sufficient flow. Water is led into
the plant by means of circulating water pumps and, after passing through the condenser, is
discharged back into the river. It is necessary to establish the correct relative position of the
intake and outfall.
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A cooling tower is a steel or concrete hyperbolic structure having a reservoir at the bottom
for storage of cooled water. Warm water is led to the top. Air flows from the bottom to top.
The water drops falling from the top come in contact with air, lose heat to the air and get
cooled.
3.4.9 Economizer
Flue gases coming out of the boilers carry lot of heat. An economizer extracts a part of this
heat from the flue gases and uses it for heating feed water. The use of an economizer results
in saving the coal consumption and higher boiling efficiency, but need extra investment
and increase in maintenance costs and flour area required for the plant. Economizer is used
in all modern power plants.
3.4.10 Relay
A relay is n electrical switch that opens and closes under the control of another electricalcircuit. In the original form, the switch is operated by an electromagnet to open or close one
or many sets of contacts. It was invented by Joseph Henry in 1835. Because a relay is able
to control an output circuit of higher power than the input circuit, it can be considered to be,
in a broad sense, a form of an electrical amplifier.
Since relays are switches the terminology applied to switches is also applied to relays. A
relay will switch one or morepoles, each of whose contacts can be thrown by energizing the
coil in one of three ways:
Normally-open (NO) contacts connect the circuit when the relay is activated; thecircuit is disconnected when the relay is inactive. It is also called a Form A contact or
"make" contact.
Normally-closed (NC) contacts disconnect the circuit when the relay is activated;the circuit is connected when the relay is inactive. It is also called a Form B contact
or "break" contact.
Change-over (CO), or double-throw (DT), contacts control two circuits: onenormally-open contact and one normally-closed contact with a common terminal. It
is also called a Form C contact or "transfer" contact ("break before make"). If this
type of contact utilizes make before break" functionality, then it is called a Form D
contact.
Motor Protection Relay This relay detects how much is the positive sequence component,
how much is negative sequence component and how much is zero sequence component. In
case negative sequence component and zero sequence component (earth fault) goes above a
certain value, it trips the Circuit Breaker.
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Fig 2.2 Relays
3.4.11. Feed Water Heater
A feed water heater is a power plant component used to pre-heat water delivered to a steam
generating boiler. Preheating the feed water reduces the irreversibility involved in steam
generation and therefore improves the thermodynamic efficiency of the system. This
reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when
the feed water is introduced back into the steam cycle.
In a steam power plant, feed water heaters allow the feed water to be brought up to the
saturation temperature very gradually. This minimizes the inevitable irreversibilityassociated with heat transfer to the working fluid (water).
3.4.12. Super heater and re heater
Fossil fuel power plants can have a super heater or re heater section in the steam generating
furnace. Nuclear-powered steam plants do not have such sections but produce steam at
essentially saturated conditions. In a fossil fuel plant, after the steam is conditioned by the
drying equipment inside the steam drum, it is piped from the upper drum area into tubes
inside an area of the furnace known as the super heater, which has an elaborate set up of
tubing where the steam vapor picks up more energy from hot flue gases outside the tubing
and its temperature is now superheated above the saturation temperature. The superheated
steam is then piped through the main steam lines to the valves before the high pressure
turbine.
Power plant furnaces may have a re heater section containing tubes heated by hot flue gases
outside the tubes. Exhaust steam from the high pressure turbine is rerouted to go inside the
re heater tubes to pickup more energy to go drive intermediate or lower pressure turbines.
3.4.13. Air Preheater
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An air preheater (APH) is a general term to describe any device designed to heat air before
another process (for example, combustion in a boiler) with the primary objective of
increasing the thermal efficiency of the process. They may be used alone or to replace a
recuperative heat system or to replace a steam coil. The purpose of the air preheater is to
recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler
by reducing the useful heat lost in the flue gas. As a consequence, the flue gases are also
sent to the flue gas stack (or chimney) at a lower temperature, allowing simplified design of
the ducting and the flue gas stack. It also allows control over the temperature of gases
leaving the stack (to meet emissions regulations, for example).
There are two types of air preheater for use in steam generators in thermal power stations:
One is a tubular type built into the boiler flue gas ducting, and the other is a regenerative air
preheater. These may be arranged so the gas flows horizontally or vertically across the axis
of rotation.
3.4.14. Protection and control Equipment
In the thermal power plant, protection and control equipments controls and protects all the
equipments of power generation process from emergency or unexpected conditions. Devices
protected are such as Boiler, turbine etc. Control devices measure and maintain other
parameters such as temperature, pressure etc.
The turbine protection system can be actuated by two methods-Hydraulic trip system and
Electrical Trip System. Both the systems, when initiated, act on hydraulic control system
and cause trip oil pressure to collapse which in turn closes the emergency stop valves,Interceptor valves and control valves.
4. Control & Instrumentation Department
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Control and Instrumentation department plays the most significant role in a thermal power
plant.
It consists of engineers from Electronics and Communication Branch. This department is
further divided into
1. Operations Department and2. Maintenance Department
Operations Department looks after the successful operation and running of power
plant. This department takes care of plant running conditions. They are responsible
for providing data at control room regarding the plant conditions and parameters such
as temperature etc.
Maintenance department is responsible for all the maintenance related tasks of plant
and control systems. Thermal power plant consists of control systems used for
controlling the plant devices. These control systems are maintained by C&IDepartment.
4.1. MEASUREMENTS IN POWER PLANTS
In a power plant number of measurements is made. These can be divided into
Electrical measurementscurrent, voltage, power, frequency, power-factor etc., Non-Electrical parameters flow of feed water, fuel, air and steam with correction
factor for temperature steam pressure and steam temperature-drum level
measurementradiation detectorsmoke density measurementdust monitor.
4.2. Control Room
From the control room, the plant operators monitor and operate the facility, via theplants Distributed Control System, with the click of a mouse, viewing graphic
representations of all MEC systems on various screens.
The system gives operators both audible and visual signals to keep them informed ofplant conditions at all times and to determine when preventative maintenance is
required.
Control Rooms are connected to plant via optical fibers. They receive real time data regarding the plant conditions such as boiler temperature,
pressure, fan speed etc.
They are used to control and monitor all the plant conditions and various parameters.
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They are used to trip boiler, primary fan, turbine and other power plant equipments incase of their regarding parameters crossing the safe limits.
4.3. Temperature Measurement
Temperature Measurements in a power plant is a very important task. If temperature of any
of the plant equipments rises above its safe limits, it would cause serious security problems
and can be a threat to plant and its workers.
4.3.1. Temperature Measurement Devices
For the purpose of temperature measurement, various devices are used depending on the
suitability and applicability of measuring devices. Some of them are thermocouples,
resistance thermometers, thermistors, bimetallic thermometers and acoustic pyrometers.
Thermocouple
Thermocouple is based on seeback effect which states that when heat is applied to a junction
of two dissimilar metals an emf is generated which can be measured at the other junction.
Fig. A thermocouple junction
Resistance Thermometer
The resistance of a conductor changes when its temperature is changed. This property is
utilized to measure the temperature.
Rt = Ro (1+dT)
WHERE = Temperature co-efficient of resistance
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dT = Temperature difference
Fig. Resistance Temperature Detector
Thermistors
Thermistors are generally composed of semiconductor materials. They have a negative
coefficient of temperature, so resistance decreases with increase in temperature.
The coefficient is as large as several % per degree Celsius. This allows the thermistors todetect small changes in temperature which could not be observed with thermocouples or
RTDs. So these are used for precision temperature measurements control and compensation.
Bimetallic Thermometers
Bimetallic Thermometers works on the principle that all metals expand or contract with
temperature and the temperature coefficient is not the same for all metals and so their rate of
expansion or contraction are different.
Fig. Bimetallic Thermometer
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Bimetallic devices are extensively used in process industries for local temperature
measurements. These are also used as cut out switch in electrical apparatus by monitoring
current flow.
Acoustic Pyrometer
Acoustic pyrometers work on the principle that the velocity of sound in a medium is
proportional to the temperature.
Gas Temperature = [ Distance / (Time * B) ]^2
Where, B=constant
4.4. FSSS Logic System
FSSS stands for Furnace Safeguard Supervisory System. It has the following major tasks to
perform:
Satisfactory Boiler Startup Startup Of Individual Oil Systems Operation Of fuel firing subject to certain conditions Protection and interlock of oil/coal system
4.5 Pressure Measurement
Pressure is defined as force per unit area. Pressure measurement is very important as high
pressure may cause accidents. For example, if pressure inside a boiler rises above the safe
limits then it may cause bursting of boiler.
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Pressure of one normal(standard) atmosphere is known as standard pressure.
Mathematically it can be expressed as:
101325 Pa / 101.325 kPa 1013.25 mbars 14.696 psia 29.921 in.Hg / 760 mmHg @ 0oC (32oF) 407.5 in.H2O / 33.958 ft.water @ 20oC (68oF)
4.4.1. Pressure Sensors
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Fig. Various Pressure Sensing Devices
In the above figure,
The basic pressure sensing element
(A): C-shaped Bourdon tube
(B): a helical Bourdon tube
(C): flat diaphragm
(D): convoluted diaphragm
(E): capsule
(F): a set of bellows
Bourdon Tube
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Bourdon tube is a sealed tube that reflects in response to applied pressure. It provides fairly
large displacements (except diaphragms).It is useful in mechanical gauges and for electrical
sensors that require a significant movement.
4.6 Turbine Protection
The turbine protection system, as the name suggests protects the turbine from any hazardous
conditions. The turbine protection system can be actuated by any of the following trip
systems:
Hydraulic Trip System Electrical Trip System
Both the trip systems, when initiated, act on the hydraulic control system and cause trip oil
pressure to collapse which in turn closes the Emergency stop valves, Interceptor valves and
control valves.
In a turbine protection system, two trip solenoids are provided in the hydraulic circuit,
which get trip signals from the electrical system. Actuation of any one solenoid is sufficient
to trip the turbine. The electrical system is configured as a 2-channel system. Each channel
is realized in a Processing Unit. Both the processor units are completely independent of each
other and input modules, processor module and output modules reside on each. Each
channel having two processors Unit with one processor in hot standby mode. Realization of
2 out of 3 trip logic is carried out in the processor. Both the channels are tested periodically
even while the turbine is running. Cyclic testing is done automatically at preset intervals
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Fig. Turbine protection system
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5. Safety Measures
In a thermal power plant, care is taken regarding the safety of the workers in the plant. All
measures are to taken to ensure that there is no accident or any sort of mishappening takes
place. It is very important to maintain the plant safety so as to maintain a good workable
atmosphere among the employees.
History gives us many examples where hundreds of lives have been lost and loss of millions
of money has occurred due to industrial accidents. Accidents like Bhopal Gas Leakage;
Mexico etc have not only destroyed peoples lives but also impacted the future generations
in the area. Effects of these accidents can be still seen in such areas. Children born in these
areas are generally born with some sort of genetic disorder.
For the individual safety of workers, following steps are taken:
They are given helmets to wear before entering the plant. They are supposed to enter the plant only if wearing shoes. They are given special training for lifting heavy loads. Annual training is given to workers for emergency cases such as gas leakage etc.
On the plant level, following steps are taken for safety:
Regular maintenance of plant equipments. Carrying on pseudo tests on all equipments such as boiler, turbine etc.
Educating labors about what to do in case of emergency such as gas leakage. Ensuring the quality and durability of devices used. Taking extra care in handling and maintenance of volatile materials such as chlorine
gas.
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6. GAS PLANT
6.1 Introduction To Gas Power Plants
The development of the sector in the country, since independence has been predominantly
through the State Electricity Boards. In order to supplement the
effects of the states in accelerating power development and to promote power development
on a regional basis to enable the optimum utilisation of energy resources, the Government of
India decided to take up a programme of establishment of large hydro and thermal power
stations in the central sec tor on a regional basis. With this in view, the Government set up
the National Thermal Power Corporation Ltd., in November 1975 with the objective of
planning, construction, commissioning, operation and maintenance of Super Thermal and
Gas Based Power projects in the country.
The availability of gas in a large quantity in western offshore region has opened an
opportunity to use the gas for power generation, which is an economical way and quicker
method of augmenting power generating capacity by natural gas as fuel in combined cycle
power plant in a power deficit country like ours. With this intention in mind the
Government asked NTPC to take up the construction of Kawas, Auraiya, Anta, Dadri and
Gandhar Gas Power Project along the HBJ Gas pipe line.
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The power plant consists of gas turbine generating units waste heat recovery boilers, steam
turbo generator, ancillary electrical and mechanical equipments. The power generated at this
power station is fed over 220 KV AC transmission system associated with this project to
distribute the power in the various Regions.
In the Power Sector, gas turbine drive generators are used.
Gas turbines range in size from less than 100 KW up to about 140.000 KW. The gas turbine
has found increasing application due to the following potential advantages over competive
equipment.
Small size and weight per horsepower
Rapid loading capability
Self-contained packaged unit
Moderate first cost
No cooling water required Easy maintenance
High reliability
Waste heat available for combined cycle application.
Low Gestation Period
Low Pollution Hazards
The function of a gas turbine in a combined cycle power plant is to drive a generator which
produce electricity and to provide input heat for the steam cycle. Power for driving the
compressor is also derived from gas turbine.
6.2 Salient Features of NTPC DADRI Gas Project
DADRI GBCCPP-STAGE I (817MW)
General Layout Plan
In the main plant block two modules, each consisting of two GTGs placed on each side of 2
STGs. The central control room is located towards west of the ST hall. The transformer yard
Is on the wester side of the turbine hall, with switchyard further down west.
Induced draft cooling towers have been located considering the proper flow of cooling
water. Nearer to main power house & convenient routing of open return channel to CW
pump house. The 220/400 KV switchyard has been located in front of the power station.
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The 220 KV switchyard control room is accommodated in the central control room itself.
Space has been kept for liquid oil installation and oil unloading facilities.
The GAIL terminal for receiving gas is located within boundary of plant site.
6.3 Gas Plant Operation
Gas Turbine, WHRB, Steam Turbine Starting Modes
Basic conditions for plant operation are as follows:-
Start up or shut down of G/T, WHRB and S/T of each module is performed separatelyfrom the other module (except for S/T gland steam back-up and heating steam back up
systems).
Start up/shut down mode is selected freely form among those mentioned.
The start up/shut down procedure for WHRB and S/T here mainly describes operating
procedure for G/T by-pass damper, WHRB inlet damper and remote operated valve
necessary for start up and shut down from G/T exhaust gas admission to WHR till rated load
operation of S/T. For detail operating procedure for G/T WHRB, S/T auxiliaries and remote
operated valve following procedures are followed.
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Start up Mode
The start up mode of G/T, S/T and WHRB shall be selected from among the following as a
rule through various other start up modes are conceivable according to power demand andoperating principle.
Normal start up mode
Rapid start up mode
G/T/WHRB additionally start up mode
Single G/T/WHRB start up mode
6.4 Combined-Cycle Power Plant
Power Generation:
Air Inlet
The amount of air needed for combustion is 800,000 cubic feet per minute. This air is
drawn though the large air inlet section where it is cleaned, cooled and controlled, in order
to reduce noise.
Turbine-Generators:
The air then enters the gas turbine where it is compressed, mixed with natural gas and
ignited, which causes it to expand. The pressure created from the expansion spins the
turbine blades, which are attached to a shaft and a generator, creating electricity.
Each gas turbine produces 185 megawatts (MW) of electricity.
The blades are attached to a rotor, which spins the generator, and makes electricity. Think of
a generator as a huge spinning magnet inside a coil ofwire. As the magnet spins, electricityis created in the wire loops.
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6.5 Heat Recovery Steam Generator (HRSG)
The hot exhaust gas exits the turbine at about 1100 degrees Fahrenheit and then passesthrough the Nooter Erickson, Heat Recovery Steam Generator (HRSG).
In the HRSG, there are 18 layers of 100-foot tall tube bundles, filled with high purity water.
The hot exhaust gas coming from the turbines passes through these tube bundles, which act
like a radiator, boiling the water inside the tubes, and turning that water into steam. The gas
then exits the power plant through the exhaust stack at a much cooler 180 degrees, after
having given up most of its heat to the steam process.
About 1 million pounds of steam per hour is generated in this way and sent over to the
steam turbine through overhead piping.
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6.6 Steam Turbine
The steam turbine is a Siemens Westinghouse KN Turbine Generator, capable of producing
up to 240 MW. It is located on top of the condenser, across from the cooling tower.
Steam enters the turbine with temperatures as high as 1000 degrees Fahrenheit and pressure
as strong as 2,200 pounds per square inch. The pressure of the steam is used to spin turbine
blades that are attached to a rotor and a generator, producing additional electricity, about
100 megawatts per HRSG unit.
After the steam is spent in the turbine process, the residual steam leaves the turbine at low
pressure and low heat, about 100 degrees. This exhaust steam passes into a condenser, to be
turned back into water.
By using this combined-cycle process, two gas turbines and one steam turbine, we canproduce a total of about 600 megawatts of electricity.
6.7 Transmission of Generated Power Onto the Grid
Transformers
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The Gas Turbine and Steam Turbine generators produce power at 13,000 volts.
The transformers take the generated 13,000 volts and transform them to 230,000 volts,
which is the required voltage needed for transmission to the nearby tower that sends power
to the substation.
A small amount of generation is directed to Auxiliary transformers which transform the
generated voltage to a lower voltage, so it may be used by the plant to power our ownpumps, fans, and motors. The Metcalf Energy Center requires 12 15 megawatts to
operate.
Switchyard
From each transformer, the power passes underground into our switchyard. The power from
all of the generators comes together there, where it is measured, metered and directed onto
the grid.The proximity of the site to a large, existing PG&E substation makes it a good place to build
a power plant and the nearest transmission tower is only about 200 feet away.
Condenser andCooling Tower
The purpose of the condenser is to turn low energy steam back into pure water for use in the
Heat Recovery Steam Generator.The purpose of the cooling tower is to cool the circulating water that passes through the
condenser. It consists of ten cells with large fans on top, inside the cone-like stacks, and a
basin of water underneath.
We process and treat the Title 22 recycled water after receiving it from the City, before
using it in our cooling tower. The cool basin water absorbs all of the heat from the residual
steam after being exhausted from the steam turbine and it is then piped back to the top of the
cooling tower.
As the cool water drops into the basin, hot wet air goes out of the stacks. Normally, hot
moist air mixes with cooler dry air, and typically a water vapor plume can be formed, one
that may travel hundreds of feet in the air and be seen from miles away. The CaliforniaEnergy Commission considered this visually undesirable in this community so we added a
Plume-Abatement feature, louvers along the topsides of the tower that control the air
flow.
The cooling tower evaporates about three-fourth of the processed, recycled water, then we
send about one-fourth of it back through the sewer lines for re-treatment by the City.
The Metcalf Energy Center purchases 3 to 4 million gallons per day of recycled water from
the City of San Jose. Evaporation of this water assists the City in adhering to their flow cap
limits and helps to protect the sensitive saltwater marsh habitat of the San Francisco Bay
environment from receiving too much fresh, recycled water.
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6.8 Water Tanks, Natural Gas Pipeline, Control Room
Water Tanks
The largest tank is the Service Water tank. It contains 470,000 gallons of water to be usedfor drinking, fire fighting and for the high purity water train. The water from the service
water tank is pumped to the water treatment building where it then passes through a reverse
osmosis unit, a membrane decarbonater, and mixed resin bed demineralizers to produce up
to 400 gallons per minute of ultra pure water.
The pure water is then stored in the smaller 365,000-gallon tank until it is turned into steam
for making electricity.
Natural Gas
Natural gas fuels the combustion turbines. Each turbine can consume up to 2,000 MMBTU
per hour.
The fuel comes from the major high pressure natural gas pipeline that runs along the east
side of Highway 101, less than 1 mile to the east of our site.
During construction, Horizontal Directional Drilling was utilized with careful
coordination with many local authorities. The pipeline was built 60 feet underground and
passed under highways, creek, train tracks, and environmentally sensitive areas.
The pipeline enters the site just behind the water tanks, where equipment regulates and
measures the natural gas composition, flow and pressure.
Gas compressors pump the natural gas though the facilities fuel gas system where it isdelivered to the gas turbine and the HRSG duct burners at the proper temperature, pressure
and purity.
Control Room
From the control room, the plant operators monitor and operate the facility, via the plants
Distributed Control System, with the click of a mouse, viewing graphic representations of
all MEC systems on various screens.
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The system gives operators both audible and visual signals to keep them informed of plant
conditions at all times and to determine when preventative maintenance is required.
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7. Technical DocumentationSALIENT FEATURES :
i) Type of Station : Combined Cycle Power Plant
ii) Station Capacity : 817 MW(2(131 x 2+146.5))130.5+154.51
iii) Fuel : Main - Natural Gas
Alternate fule - HSD
iv) Source, Gas Transportation : HaziraConsumption : Through HBJ Pipe Line 4.0 MCMD
v) Cooling Water source : Upper Gange Canal Dehra
headwork. During closer of UGC
through network of tubewells.
vi) Startup Power : Black Start DG set 2.6 MVA
capacity.
vii) Heat rate- open cycle : 2692 Kw / Kwh
Combined cycle : 1748 Kw / Kwh
Specific Gas : Open cycle - 0.3167m3/ Kwh
Consumption : Combined Cycle - 0.205m3/ Kwh
viii) HP/LP bypass capacity : 100% MCR
(for steam turbine only)
ix) Efficiency
Open cycle : 32%
Combined cycle : 48.33%
Time required form barring
Speed to synchronisation : 4 min
Time required form synchronisation
To base load at normal Gradient : 16 min.
At Fast Gradient : 9 min.
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CONTROL AND INSTRUMENTATION
1.0
C&I SYSTEM : SAILENT FEATURE
1.1 Supplier/ make : siemens AG
1.1.1 Type : Digital Process control teleperm-ME
Sub-Systems
a) Automation sub systemAS220E/EHF
Functions : Signal conditioning, Automation, controls,
Monitoring & Protection interlocks.
AS220 EHF Special Features :
Triple redundant central processing units for processing signals in two out of three
logic.
b) Sub- system AS 231Functions : Monitoring, Alarms and calculation for GTs
c) Sub system OS254Functions : Centrialised operation & monitoring.
1.1.2. Information system Madam - SType : SICOMP M 26
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Functions : Monitoring, information displays logging and
Performance calculations.
1.1.3 OscillostoreFunctions : Sequence of events recording.
1.1.4 Bus SystemType : CS275
Functions : Inter connection (coupling) of various C&I
Systems.
1.1.5. Electro Hydraulic governing system Controls for GT units.Type : Iskamatic
1.1.6 Gas Filtration Plant InstrumentationSupplier : M/s. Siemens AG
Make : Alpha, Germany
Functions : Gas filtration plant (measurements and control)
1.1.7 Uninterupted Power Supply (UPS)Supplier : Siemens AG
Make : Gustav Klien
1.1.8 CCR InstrumentationSupplier/ make : Siemens, AG
Type : Mosaic Tile system- 8RU
1.2.0 Supplier/ Make : BHEL
1.2.1 EAST Pkg : Electronic Automation System for turbine
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- Type : ISKAMTIC
- Functions : Steam Turbine Electro Hydraulic governing
system cotrol, seal steam controls, measurements
autosynchroniser and load shedding relay.
1.2.2 HP/LP bypass system Controls.Type : ISKAMATIC.
1.2.3 Steam and water analysis systemSupplier : BHEL
Primary sample conditioning system
Make : Lowe UK
Analysers section : Polymetron France
No of analysers (per module)
Silica : 5 Nos.
Dissolved Oxygen : 4 Nos.
Conductivity : 19 Nos.
PH : 6 Nos.
Sodium : 5 Nos.
Hydrazine : 2 Nos.
Recorders : 19 Nos.
Alarm System
Type : Microprocessor based
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Make : Rochester Instruments, Scotland.
Chiller units
Make : Conair Churchill
Capacity : 2 x 100%
3.1 Fire protection systemSupplier : Siemens Ltd.
Sub vendor : Techno Equipment
Type
i) CO2 system : For GT combustion chambers lube oil
skid and fuel oil injection skid
ii) Halon System : For CCR, Computer room, control equipment
rooms and electrical switchgear.
iii) Deluge System : For transformers.
2.0 System Details :
2.1 AS 220 E :AS 220 E is the basic system with a single central processing unit where open loop controls
and protections are implemented. I/O modules are used for drive controls & close loop
controls.
2.2 AS 220 EHF :
The AS 220 EHF is functionally divided into a triple redundant central unit.
Central Processors : 2 out of 3 technique with complete self
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Monitoring microprogrammed.
Data bus : 8 bit
Power supply : + 24 V DC, 25 amps, redundant
No of I/O modules which can be plugged max 162
2.3 0S254EK
The operation & monitoring system OS254EK is bus coupled component of the
Teleperm ME. Two no. of OS254EK are provided per module.
TECHNICAL DATA
Hardware :
(1) Central Processor : Microprogrammed
(2) Data bus : 16 bit wide
(3) Main memor(DRAM) : 2048 Bytes
(4) Dot graphics : Dot resolution with max 64 x 1000 dots
(5) Operation Channel : max 2
(6) Printer : 1 No. each.
Software :
(1) Information mode(NOBI)
Display Type : Plant overview, area display, group displays,
Sub ordinate group display, individual display,
Functions display.
- Maxm. Nos possible- Area : 12-
Groups per area : 24
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Control tiles & displays per gourp 16
Updating cycle 21 Sec
- Output cycle for process operations commands: 250 ms
- Time interval between command output & statusFeed back display : 400 msec
- Display selection time
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Capacity : Max. 256 binary signals
Resolution : 1 msec.
Sequential memory : Approx. 800 signals
2.5 Data Acquistion SystemMadam- S (Sicomp M-26)
Technical Data :
Central Processor : ZE 02 16 Parallel
Processing
RAM : 8 MB.
Data retention after : >5 hrs. at max. capacity
Power failure
Serial interfaces : 3xX.27 or TTY terminal
1xV.27 or TTY printer
Floppy disc drive : 1.2 MB
Hard disk : FP 41 E 350 MB
Magnetic Tape cartridge : MK 82 Q 150 MB
Binary Inputs Capacity : 3650
Analog inputs capacity : 600
Features available
i) Bar chart displayii) Trend display 8 mts, 80 mts, 8Hiii) Mimicsiv) Alarms informationv) Status display of binary signalsvi) Logging of parameters
Through Operating log 0.5H, 1.0H, 2.0H.
vii) Sequence of Eventsrecording through incident review log.viii) Performance calculations
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ix) Other important logsAlarm & switching logs
Binary signal status log
Analog group log
Event count log
Alarm count log
Operating System : BS-M & Amboss- G
2.0 System ConfigurationNo of group Controls : 12
No of OLCS : 63
No of CLCS : 20
System Redundancy :
1) AS 220 EHF used for protection (GTs, WHRBs & STs) is triple redundant.2) Parallel operation for all subgroup & group controls are available from CRT and
pushbutton on the MIMIC panel.
4.0 Protection interlocks :
4.1 Gas Turbine
Gas Turbine Protection Trip initiating Signals
____________________________________________________________________
sl.no. Description Set Value Remarks____
1. Overspeed (Emergency- >55 Hz Mech. Trip
governor operated)
2. Axial shift high >+/- 1 mm mech. Trip
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(Thrust bearing trip-operated)
3. Compressor anti surge protection 425rpm
4. Bearing temp. V. high >120oC 2 out of
(turb./compressor/ 2 logic
Generator bearings)
5 Bearing vibration V. high >11 mm/sec -- do --
(Trub./Compressor/
Generator Bearings)
6. Flame off --- 2 out of 2 logic
7. Bearing oil pressure 70
oC 2 out off
ii) Comb. Chambers > 90oC 2 logic
9. Manual Trip ---
10 Trub. Outlet temp. V.high Variable set 2 out off
point 2 logic
(based on
ambient temp.)
11. Fuel gas pr. Low < 12.2 bar
Shut down- Initiating Signals
L.O. oil tank level low
Salient feature of Protection system
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1. Redundancy in sensors for important protection functions. (bearing temp., Turb
outlet temp, flame protection , fire protection.)
2.
Processing of processing functions in 2 channels with 2 out of 2 voting logic. In theenvent of fault in one channel, protection logic is automatically changed to 1out of 1
logic.
3. Processing of protection functions in central unit with 2 out of 3 voting logic.4.1.1. GT Auxillaries.I) Diffusion burner valves open s oni) Turbine outlet temp. calculated 0 %3) Premix burner valves Conditions for pre-mix burner openi) Turbine outlet temp. calcualted > 500 oCii) Air controller (L&R) on Autoiii) Fuel Gas Pressure > 14.5 Bariv) Turbine speed >49 Hz.v) Fuel gas Diffusion burners openvi) Fuel oil ESV Closedvii) Air controller - No Faultviii) Mixed operation not activeix) Fuel Gas shut off - No faultx) Pilot burner control onxi) Pilot burners open4) Pilot burner valves
Release conditions for open
1) Fuel Gas ESV open2) 220 KV circuit brearer on3) Speed > 49 Hz.
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4.2.0 WHRB
Trip initiating signals (provided GT is in operation )
1) LP drum level < - 700 mm (2/3 logic)2) LP drum level high > 950 mm (2/3 logic)3) LP circulating pump DP 5600C13) LP by P. prot.14) HP by P. Prot.15) HP drum level 910 mm (2/3 logic)17) HP circulating pump DP < 0.5 bar (2/3 logic)
4.2.1 WHRB Auxillariesi) HPCC pumpsRleases for start of pump
_____________________________________________________________________
S.NO. Description set value Remarks
______________________________________________________________________
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1. HP drum level. Or blr. Damper > Min 3 2/3 logicNot closed Trip initiating signals - 650 mm
Trip initiating signals.
______________________________________________________________________
S.NO. Description set value Remarks
______________________________________________________________________
1. Motor bg. Temp Hi > 80 Deg.C -
2. Motor winding temp Hi > 110 Deg.C -
3. HP Drum level low < (-750 mm) Time delay 2/3 logic
2- Sec.
4. HPCC pumps DP < 0.5 bar
II) LPCC pumps
Releases for start of pumps
_____________________________________________________________________
S.NO. Description set value Remarks
_____________________________________________________________________
1. LP Drum Level > -600 mm 2/3 logic
or Blr. Dampers not closed
Trip initiating signals.
_____________________________________________________________________
S.NO. Description set value Remarks
_____________________________________________________________________
1. LP drum level low
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2 sec.
2. LP circ. Pumps DP < 0.8 bar Time delay 3 sec after
start of pps 2/3 logic
III) HP drum level interlocks.
____________________________________________________________________
S.NO. set value Action
____________________________________________________________________
1. -350 mm Fill Level
5. 710 mm. HP drum level high alarm
HP drum drain valves Auto open
7. > 760 mm Protection open HP drum drain valves.
8. < 760 mm Release for opening HP feed control station
isolation valves
9. > 810 mm HP drum level V. high alarm Protection close
HP feed control station isolating valves.
10. > 860 mm Protection close HP economiser inlet valve
11. >910 mm HP drum level high Protection WHRB Trip
HPBFPs Trip.
12. < 910 mm Release for HPBFPs start.
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(iv) LP drum level interlocks____________________________________________________________________
S.NO. set value Action
____________________________________________________________________
1) 800 mm LP drum level high alarm Protection close
LP drum drm. valve
7) < 800 mm Release for opening LP feed control station
isolating valves.
8) > 850 mm LP drum level v. high alarm potection close LP
feed control station isolating valves
9) > 900 mm LP economiser inlet valve protection close.
10) > 950 mm LP drum level high protection WHRB trip
LP BFPs trip.
11) < 950 mm Release for LPBFPs start.
4.3 Water steam Cycle Equipment :
i) Cooling water pumps :
Releases for start of Pump
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___________________________________________________________________
S.NO. Description set value Remarks
___________________________________________________________________
1. CW inlet & outlet V/Vs ond. Left open
OR CW inlet & outlet V/Vs cond.
Right.
2. Disch. VV Closed
3. Sump level > 207.8 m
4. Bearing Temp.(pump/ motor)Trip initiating signals
_____________________________________________________________________
S.NO. Description set value Remarks
_____________________________________________________________________
1. Sump level too low - -
2. Pump bearing temp. v. high - -
3. Motor bearing temp. v. high - -
4. Discharge valve closed - -
5. Bearing vibration v. high Two out of two logic.
6. Discharge header pressure v. high Sequential trip.
7. Discharge pressure low - -
8. Condenser inlet/ outlet valve closed - -
CW pump discharge valve closes on protection after pump tirp.
ii) ACW PumpsReleases for start of Pumps .
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____________________________________________________________________
S.NO. Description set value Remarks
____________________________________________________________________
1. Suction V/V open - -
2. Disch. V/V closed or one /more - -ACW pps on.
3. ACW suct. Pr.>Min or(ACW - -
n-let Hdr. Pr.>Min & (One/ more
ACW pp ON & its disch. Valve open)
(interconnecting v/v also in case of
CWP3)
Trip initiating signals
____________________________________________________________________
S.NO. Description set value Remarks
____________________________________________________________________
1. Suction V/V closed - -
2. Discharge V/V closed - after time delay of
15 sec.
3. Suction pr. < min 0.25 2/3 logic
iii) C.E.P.Trip initiating signals :
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1. Hotwell level very low 10 bar4. Condensate flow > 31 kg/s or Min. recirculation CV bypass open or5. GSC bypass valve open or GSC inlet & outlet valve open.
iv) L.P.B.F.P.Release for start of pump1. Suction valve open2. Discharge valve closed or discharge header pressure > 10 bar
Trip initiating signals :
1. LP drum [v] Boiler 1 > 950 mm2. LP Drum [v] Boiler 2 > 950 mm3. Dearator [v] < MIN2v) H.P.B.F.P.
Release for start of pump
____________________________________________________________________
SL.NO. DESCRIPTION SET VALVE
____________________________________________________________________
1) (Disch. Valve close & Closed
Disch. Valve int. byp closed)
OR disch. Hdr. Pr.>Min 50 bar
2) L.O. pr. Common hdr. >min 2 bar
3) Recirculation v/v open open
4) lub oil tank level > min 600 mm
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5) Suction valve open open
Trip initiating Signals :
____________________________________________________________________
S.NO. Description set value Remarks
____________________________________________________________________
1) HP drum level WHRB3 >Max 4 >910 mm 2/3 logic
2) HP drum level WHRB4 >max 4 > 910 mm 2/3 logic
3) Deacrator [v]max2 85oC -
(BP/BFP/Motor brgs.)
5) Motor wdg. Temp v. high 110oC -
6) 6 suct- disch diff temp v.high 15oC -
7) L.O. com. Hdr. Pr. V. low 1 kg/cm2 2/3 logic
8) Recirc.VIv not open & 23.6 kg/s 1/2 logic
suct. Flow
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Fire protection ch.2 operated
viii) Turning GearProtection open initiating signals :
1.
Fire protection ch 1 operated2. Fire protection ch 2 operated3. Jacking oil pump 1 on or JOP 2 on, speed < 0.15 hz and seal ring TE(EE)
pressure < MIN
4. Vacuum breaker
ix) R.F.T. inlet v.v.Auto opening command at RFT [v] + 250 mm and
Protection close command at RFT [v] > 850 mm
(from CWA/CWN panels)
4.4 Steam Turbine :
Steam Turbine Protections
1) Turbine vacuum protection Condenser vacuum -0.7 bar(2/3 logic)(enable- turbine speed > 95)
2) Lube oil pr.Lube oil pressure ,1.1 bar (2/3 logic)
3) Shaft position prot.Turbine shaft displacement >+/- 1 mm (1/2 logic)
4) Oil tank level prot.Oil tank level MAX (2/2 logic)
5) Gen. Prot. Cold gasCLd gas temp after cLr.
A/B/C/D > 50 Deg C (2/2 LOGIC)
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7) HP Exh. Stm. Temp prot.
HP inner casing 100% temp > 400 Deg C (2/2 logic)
8) Wet steam prot. 1 (WHRHB 1)
HP stm. Temp < 20 Deg.C less than saturation temperature (1/2 logic)
Enable HPCVI 0% HPCVI2 0% or lift set point turb. Contr. 0%
9) wet steam prot. 2 (WHRB 2)
10) WHRB 1 Trip & (M.S. Stop V/V WHRB 2 closed or BLr. Inlet dampers WHRB 2
closed
11) WHRB 2 trip & (M.S. Stop V/V WHRB 1 closed or BLr. Inlet dampers WHRB 1
closed)
12) man Turb. Trip 1 : CWA pn. 1.
13) Man Trub. Trip 2 : - do-
14) Man Trub. Trip 1 : CWN pn. 1
15) man Turb. Trip 2 : -do-
16) Fire prot. PB 1 : CWA pn. 1
17) -do- 2 : - do-
18) -do- 1 : CWN pn. 1
19) -do- 2 : -do-
20) Elect. Gen. prot 1
21) Elect. Gen. prot 2Wet steam Temp. Prot. Variable set points
Pr. (kg/Sq. cm) Temp. (Deg. Set point)
30 : 239
35 : 246
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40 : 253
45 : 260
50 : 265
55 : 270
60 : 275
65 : 289
4.2.1 HP/LP ProtectionsTrip initiating signals
______________________________________________________________________
S.NO. Description set value Remarks
______________________________________________________________________
I. Cond. Vacuum protection
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Fire protection ch 1 Operated
Fire Protection ch 2 operated
ii) Emer. Oil Pump (DC)Protection Start
On lube Oil pressure
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Features :- Actuation of CO2 release on sensing fire after a time delay of 30 sec.
- Audio/ Visual annunciation of CO2 release in Local/CCR-
Open & short fault monitoring ..- Manual release of CO2 from local EPB without time delay- Selector switches provided fori) Auto / Manual release of CO2ii) Main / Stand by CO2 cylinderiii) CO2 release operation Isolate/ Inhabit from panel/ local.2) Halon system :
________________________________________________________________
Area No of I.S.D Detectors OSD
________________________________________________________________
GT containers 56 56
Stack containers 20 20
CCR/DAS room 51 51
Fire Protection room
Relay room 22 22
Battery room 3 3
Below false floor,
Relay room 15 15
Switchgear Room 23 23
Static Ecitation Room
ST1/ST2 8 8
Halon Panels
No of Halon
Actuator modules 30
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Features :- Initiation of Halon release on sensing fire after time delay of 30 S
(configured in 2 out of 2 logic)
- Manual release of Halon through local EPB without time delaySelector switches Provided .
i) Auto/ manual mode for halon releaseii) Isolate/ Inhabit mode for prevention of superious halon release.iii) Main / Std by Halon cylinders.4) Fire Detection & Alarms____________________________________________________________________
Area No. of ISD Detectors OSB Remarks
____________________________________________________________________
- Black start DG room 6 - -
- Cable gallery - - LHS cable is also
provided
- Fuel unloading
station - - 16 nos ROR detectors
are provided.
- Module PP house 36 - -
- AC plant 14 - -
Linear heat sensor cable for sensing fire in cable gallary provided
For Auto/ Visual annunciation of fire local Repeater panels are provided.
4) Central Fire Monitoring System
Features 1) Display of Fire alarms and fault signals fo total plant area in
CCR through microprocessor based system Monitor.
ii) Hard copy print out of alarm & fault signals through printer.
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7.2 Air Compressor system : Mode of operatioin of compressors:
i) Continuous run - load un load regulation
- Motor runs continuously- Compressor gets unloaded by 50% at reciever Pr. > 8.4 Kg/Cm Sq.- 100% at receiver Pr. > 8.7 Kg/Cm Sq. Compressor gets loaded by- 50% at receiver Pr. < 8.2 Kg/Cm Sq.
100 % at receiver Pr. < 7.9 Kg/Cm Sq.
2) Auto Start Stop regulation :-
Compressor starts automatically at air receiver
Pr. < 7KG/Cm Sq.
Compressor gets unloaded at air receiver pr. < 7.8 Kg/cm2 remains unloaded, the
motor stops.
Compressor Protections
_____________________________________________________________________
S.NO. Description set value
_____________________________________________________________________
1. Lube Oil pressure low 2 Kg/Cm Sq.(Time delay 15 sec.)
2. HP delivery volume 8.9 Kg/Cm Sq.
3. Air Pressure separator 8.9 Kg/cm Sq.
4. Cooling water inlet flow very low 230 Lts/Min
5. HP delivery volume bottle air temp. High 163oC
6. Moisture separator air temp. high 48oC
7. Compressor outlet cooling water temp. high 48oC
8. Lube oil temp. high 67oC
9. Motor over load
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Air Drying Plant
Sequence of Operation
Step No time Action
1 ---- SVI on SV2 ON\
2. 1 min (adsorber A i/s) (adsorber B i/s)
SV1 Off SV2 Off
SV4 On SV4 on
(depressurised B) (Depressurised A)
3. 15 min SV4 off SV4 off
SV3 on SV3 on
Pre- selected blower (s) on Pre-selected blower (s) on
4. 16 min (react. Ads B) (Reacti. Ads A)
5. 4 hrs. 16 min. Heaters off Heaters off
6. 5 hrs 16 min. blowers off blowers off
SV3 off SV3 off
7. 7 hrs. 45 min SV5 on SV5 on
8. 8 hrs. (Repressurised B) (Repressurised A)
SV5 off SV5 off
Memory reset memory reset
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7. Conclusion
NTPC plays a very vital role in total power supply in our nation. It is one of the largest
PSUs in our country.
As a trainee, when I first went there I wasnt sure about what I will get to learn considering
my branch of engineering. But, when I went there all my doubts were removed. It was a
great experience working at NTPC with one of the finest engineers in our country. I got to
learn a lot from them regarding the plant operation and maintenance. I learned about control
systems and high speed data communication from plant sites to control room. Also, got to
learn about management skills from department managers. We had interactive sessions with
the engineers as well as labors working in the plant.
This industrial visit helped me to familiarize with industrial environment. It helped me tovisualize many of the concepts that were only available in theoretical form in books. Overall
it was a great experience at NTPC.
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8. References
Device Manuals provided at NTPC http://www.ntpc.co.in http://www.wikipedia.com
http://www.ntpc.co.in/http://www.ntpc.co.in/http://www.wikipedia.com/http://www.wikipedia.com/http://www.wikipedia.com/http://www.ntpc.co.in/