Summer Training At

NTPC (DADRI)

SUBMITTED BY - SUBMITTED TO -UTSAW GUPTA Miss. Deepti YadavEE - Third year EE Deptt..Roll. No. - 1205220048

CONTENT

About NTPC Installed Capacity Sources Training phase

About NTPC

NTPC is India’s largest energy conglomerate with roots planted way back in 1975 to accelerate power development in India.

NTPC became a Maharatna company in May 2010, one of the only four companies to be awarded this status.

NTPC was ranked 431st in the ‘2015, Forbes Global 2000’ ranking of the World’s biggest companies.

The total installed capacity of the company is 45,548 MW (including JVs) with 18 coal based and 7 gas based stations. 7 Joint Venture stations are coal based and 8 renewable energy projects and 1 hydro project.

Although the company has 17.73% of the total national capacity, it contributes 25.91% of total power generation due to its focus on high efficiency.

INSTALLED CAPACITY

NTPC - Dadri

TOTAL CAPACITY OF DADRI POWER PLANT :-(A) THERMAL (B) GAS I:- 04X210 MW = 840 MW I:- 04X130.19 II:- 02X490 MW = 980 MW II:- 02X154.51

TOTAL = 1820 MW TOTAL = 817 MW

(C) SOLAR = 05MW

GRAND TOTAL = 2642 MW

SOURCES

Coal source

- Piparwara mine , Jharkhand

- Requirement = 13000 MT/day

Water source

- Upper Ganga Canal

Gas source

- HBJ Pipeline (a major gas pipeline of GAIL)

Hazira-Bijaipur-Jagdishpur

Training Phase

1. Thermal power station 2. Switchyard station

1. THEMAL POWER STATIONLayout

Basic Working of Thermal Power Plant

Working of a Thermal Power Plant

The coal is brought and crushed to powder. This is feed to boiler for producing heat . In Boiler the water is converted to steam. In Superheater the moisture content is removed from the steam and that steam is called super heated

steam. The superheated steam rotates the shaft of the High Pressure(HP) turbine. The exhausted steam is sent to Reheater and the steam then rotates the Intermediate Pressure (IP)

turbine. The steam from the IP Turbine is then feed to Low Pressure(LP) turbine. The turbine shaft is connected to the Generator, which produces electric power. The steam expanded in turbine is condensed in a Condenser to be feed into the boiler again.

Basic Power Plant Cycle

COAL HANDLING PLANT

The stone and unwanted coal

are rejected

Stack & Reclaimer – It is used to store the powdered

coal for emergency purpose.

Atmospheric air –Through FD

fan

BOILER

A Boiler is a closed vessel in which water is heated to produce steam by utilizing the heat generated by coal combustion.

Boilers are classified into two types based on relative position of water and hot gases :-

Water tube boilers Fire tube boilers

In Water tube boiler, water flows through tubes and hot gases of combustion flow over these tubes. This is high pressure boilers.

In Fire tube boiler, the hot products of combustion

passes through tubes surrounded by water . This is low pressure boiler.

In Dadri power plant, Water tube boiler is used.

Saturated steam is generated at a pressure of around 2000-2200 KPa.

It is then heated in Superheater.

Auxilliary Components Of a Boiler

Superheater Economizer Air-preheater Reheater Deaerator

Superheater

Superheaters are used to raise the steam temperature above the saturation temperature by absorbing

heat from flue gases to increase plant efficiency. It removes last traces of moisture and therefore prevents turbine blades from corrosion. Outlet temperature and pressure of steam coming out from the superheater is 540 °C & 157 kg/cm²

Economizer, Air-preheater & Reheater

An Economizer is a heat transfer device used for heating

the feed water with the help of hot flue gases. It improves the efficiency of the power plant. Air-preheater is a device which utilizes the waste heat

of the flue gases leaving the Economizer for heating

the air required for combustion. Reheater is used to increase the temperature of exhaust

steam from HP turbine by utilizing the heat of the hot

flue gases leaving the chimney.

Deaerator

A steam generating boiler requires that the boiler feed water should be devoid of air and other dissolved gases, particularly corrosive ones.

In order to avoid corrosion of the metal, power

station uses a Deaerator, for the removal of air

and other dissolved gases from the boiler

feed water. A Deaerator has a vertical, domed deaeration section

mounted on top of a horizontal cylindrical vessel

which serves as a deaerated boiler feed water storage

tank.

PRIME MOVER(TURBINE)

A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and

converts it into mechanical energy. About 86% of all electric generation in the world is by use of steam turbines. In a thermal power plant generally 3 turbines are used to increase the efficiency. High Pressure Turbine(HPT): The superheated steam is directly fed to this turbine to rotate it. Intermediate Pressure Turbine (IPT) : The output from the HPT is reheated in a reheater and used to

rotate IPT. Low Pressure Turbine (LPT):The Exhausted steam from the IPT is directly fed to rotate the shaft of LPT. All the turbines are connected to a single shaft which is connected to the generator.

CONDENSER

It condenses the steam at the exhaust of the turbine

with the help of cooling water. It creates a very low pressure at the exhaust of turbine,

this helps in converting heat energy of the steam into mechanical energy in the prime mover.

Condensed steam can be used as feed water to the boiler.

COOLING TOWER

Removes heat from the water discharged from the condenser so that the water can be discharged into the river or recirculated or reused.

Air can be circulated in the cooling tower through natural draft and mechanical draft.

ELECTROSTATIC PRECIPITATOR (ESP)

Top view Side ViewIt is a device which removes dust or other finely divided particles from flue gases by charging the particles inductively with an electric field, then attracting them to highly charged collector plates. Also known as precipitator. The process depends on two steps. In the first step the suspension passes through an electric discharge (corona discharge) area where ionization of the gas occurs. The ions produced collide with the suspended particles and confer on them an electric charge. The charged particles drift toward an electrode of opposite sign and are deposited on the electrode where their electric charge is neutralized. It has an efficiency of 99.8 % and it is a very high power consuming device of about 1 kwh for 10 thousand m³ of flue gas.

PRIMARY AIR FAN (PAF)

Air to blow the coal from the mill to the boiler, called the

primary air, is supplied by a large fan driven by a variable

speed motor. When mixed with a stream of air the powdered coal

behaves more like a gas than a solid. Primary air does two jobs – heating the coal powder and

secondly lifting it into the furnace through pipelines.

INDUCED DRAUGHT (ID) FAN

It is draws out hot flue gases from the boiler. The gas has already passed out from Air-

preheater and Electrostatic precipitator before it reaches ID fan.

The heat from the flue gases or smoke is used in the air heaters to heat up the primary and secondary air.

CHIMNEY

The chimney is 275 meters' high and 50,000 tonnes of reinforced concrete were used to make it.

It consists of flues each of which serve typically two or three boilers.

It is used to discharge flue gases at high

altitude.

ELECTRICAL EQUIPMENTS

Alternator An alternator is coupled to a steam turbine and converts mechanical energy of turbine into electrical energy. It may be Hydrogen or Air cooled. The necessary excitation is provided by main and pilot exciters directly coupled to the alternator shaft. Transformer Main step- transformer : steps up generated voltage transmission of power. Station transformer : general purpose Auxilliary transformers : which supply to individual unit auxiliaries. Control Room and Switch yard The control room monitors the overall operation of the plant. It is provided with safety relays and switch gears.

ASH HANDLING PLANT

The percentage of ash in coal is 5% in good quality coal & about 40% in poor quality coal.

Power plants generally use poor quality of coal , thus amount of ash produced by it is quite large.

A modern 1000MW plant produces about 4800 tons of ash daily.

The stations use some conveyor arrangement to carry ash to dump sites.

COAL ASH CAN BE USED IN

Fly Ash Bricks / Blocks Cement Concrete Road construction Embankment / Back fills / Land development Use in agriculture Mine filling

2. SWITCHYARD STATION

Switchyard means collection of electrical equipment, where high voltage electricity is switched using of various component.

Electrical switchyards are usually part of a substation where electricity is transformed from one voltage to another for the transmission, distribution.

ELECTRICAL EQUIPMENTS

Electrical Power transformers Instrument transformers Conductors & Insulators Isolators Bus bars Lightning arresters Circuit breakers Relays Capacitor banks miscellaneous equipment

Electrical Power Transformer

Cont..

A static electrical machine used for transforming power from one circuit to another circuit without changing frequency is termed as Power transformer .The transformers are generally used to step down or step up the voltage levels of a system for transmission and generation purpose.

These transformers are classified into different types based on their design, utilization purpose, installation methods.

Instrument transformers

Current transformer

Current transformers are basically used to take the readings of the currents entering the substation.

This transformer steps down the current from 800 amps to 1 amp.

This is done because we have no instrument for measuring of such a large current

Potential transformer

Potential transformer is quite similar to the current transformer, but it is used for taking samples of high voltages of a system for providing low-voltage to the relays of protection system and also to the low-rating meters for voltage measurement.

Using this low-voltage measurement, the actual system’s high voltage can be calculated without measuring high voltages directly to avoid the cost of the measurement system.

Conductor

The material or object that obeys the electrical property conductance (mostly made of metals such as aluminum and copper) and that allows the flow of electric charge is called conductor.

Conductors permit free movement of the flow of electrons through them. These are used for the transmission of power or electrical energy from one place (generating station) to another place.

Conductors are of different types and mostly aluminum conductors are preferred in practical power systems.

Insulators

Cont..

The metal which does not allow free movement of electrons or electric charge is called as an insulator. Hence, insulators resist electricity with their high resisting property. There are different types of insulators such as suspension type, strain type, stray type, shackle, pin type and so on. A few types of insulators are shown in the above figure. Insulators are used for insulation purpose while erecting electric poles with conductors to avoid short circuit and for other insulation requirements.

Isolator

Cont..

Isolator is a manually operated mechanical switch that isolates the faulty section or the section of a conductor or a part of a circuit of substation meant for repair from a healthy section in order to avoid occurrence of more severe faults. Hence, it is also called as a disconnector or disconnecting switch. There are different types of isolators used for different applications such as single-break isolator, double-break isolator, bus isolator, line isolator, etc.

Busbar

Cont..

The conductor carrying current and having multiple numbers of incoming and outgoing line connections can be called as bus bar, which is commonly used in substations. These are classified into different typesSingle bus Double bus Ring bus.

Lightening Arresters

Cont..

The substation equipments such as conductors, transformers, etc., are always erected outdoor. Whenever light surges occur then, a high-voltage pass through these electrical components causing damage to them (either temporary or permanent damage based on the amount of voltage surge). Therefore, to avoid this difficulty, lightening arresters are placed to pass the entire lightening surges to earth. There are other arresters which are used to ground the switching surges called as surge arresters.

Circuit breakers

Cont..

A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow.It can make or break a circuit either manually or by remote under normal or fault conditions.Actuator lever - used to manually trip and reset the circuit breaker. Actuator mechanism - forces the contacts together or apart,Contacts - Allow current when touching and break the current when moved apart Terminals Bimetallic strip.

Cont..

Circuit breaker are used for all type of voltage.It is using in high power laboratories.It is using outdoor as well as indoor.Mostly used circuit breakers are Oil circuit breaker, Air circuit breaker, SF6 circuit breaker, Vacuum Circuit Breaker, and so on.

Relays

Cont..

Relays are used for disconnecting the circuits by manual or automatic operation using circuit breakers.Relay consists of the coil which is excited or energized and such that making the contacts of relay closed activates the relay to break or make the circuit connection. There are different types of relays such as over current relays, definite time over current relays, voltage relays, auxiliary relays, reclosing relays, solid state relays, directional relays, inverse time over current relays, microcontroller relays, etc. The above figure shows some basic relays and their operation.

Capacitor banks

Cont..

A Capacitor bank is a set of many identical capacitors connected in series or parallel within a enclosure and is used for the power factor correction and basic protection of substation. These capacitor banks are acts as a source of reactive power, and thus, the phase difference between voltage and current can be reduced by the capacitor banks. They will increase the ripple current capacity of the supply. It avoids undesirable characteristics in the power system. It is the most economical method for maintaining power factor and of correction of the power lag problems

Miscellaneous equipment

Emerging trends in technological development have created advancement in the substation installation and maintenance. For example, SCADA (supervisory control and data acquisition) technique made it possible to control a substation automatically from a remote location.

REFERENCE

 NTPC bookletTraining classes Training visit

THANK YOU