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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/