Final Report - Ntpc

7/30/2019 Final Report - Ntpc

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- Ankit Kamal

- Anurag Kamal


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ABSTRACT

To meet the power demands of the country, it is required to set up new projects,

time to time so that demand and generation gap may be narrowed but most

important is to full utilization of existing capacity. This may be possible only by

increasing the reliability, availability and maintainability of power generation units

and by operating the units at its full capacity.

This vocational training report is concerned with the overall operation of

the plant, machines used in the plant, water treatment in the plant and

thermodynamic cycles used in the NTPC, Auraiya Gas Power Plant.


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CONCLUSION

THE COMPANY

NTPC Limited is the largest thermal power generating company of India. A public

sector company, it was incorporated in the year 1975 to accelerate power

development in the country as a wholly owned company of the Government of

India. At present, Government of India holds 89.5% of the total equity shares of

the company and the balance 10.5% is held by FIIs, Domestic Banks, Public and

others. Within a span of 30 years, NTPC has emerged as a truly national power

company, with power generating facilities in all the major regions of the country.

Based on 1998 data , carried out by data monitor UK, NTPC is 6th

largest in terms

of thermal power generation and the second most efficient in terms of capacity

utilization amongst the thermal utilities in the world.


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NTPC Ltd. IN INDIAN POWER SECTOR

NTPCs core business is engineering, construction and operation of power

generating plant and also providing consultancy to power utilities in India and

abroad. As on date the installed capacity of NTPC is 24,954 MW through its 14

coal based (20,685 MW), 7 gas based (3,955 MW) and 3 joint venture projects

(314 MW). NTPC acquired 50% equity of the SAIL Power Supply Corporation

Ltd. (SPSCL). This joint venture company operates the captive power plants of

Durgapur(120 MW), Rourkela(120 MW) and Bhilai(74 MW). NTPCs share on 31

march 2006 in the total installed capacity of the country was 19.51% and it

contributed 27.68% of the total power generation of the country during 2005-06.

NTPC has set new bench marks for the power industry both in the area of

power plant construction and operation. It is providing power at the cheapest

average tariff in the country. With its experience and expertise in the power sector,


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NTPC is extending consultancy services to various organizations in the power

business.

INSTALLED CAPACITY

AN OVERVIEW

Projects No. of Projects Commissioned

Capacity(MW)

NTPC OWNED

COAL 14 20,685

GAS/LIQ FUEL 07 3,955

TOTAL 21 24,640

OWNED BY JVCS

COAL 3 314*GRAND TOTAL 24 24,954

*Captive Power Plant under JV with SAIL

PROJECT PROFILE

Coal Stations

Coal Based State Commissioned

Capacity(MW)

Singrauli Uttar Pradesh 2,000

Korba Chhattisgarh 2,100

Ramagundam Andhra Pradesh 2,600

Farakka West Bengal 1,600

Vindhyachal Madhya Pradesh 2,260

Rihand Uttar Pradesh 2,000Kahalgaon Bihar 840

NTCPP Uttar Pradesh 840

Talcher Kaniha Orissa 3,000

Unchahar Uttar Pradesh 840

Talcher Thermal Orissa 460

Simhadri Andhra Pradesh 1,000


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Tanda Uttar Pradesh 440

Badarpur Delhi 705

Total (Coal) 20,685

Gas/Liq. Fuel Stations

Gas Based State Commissioned

Capacity(MW)

Anta Rajasthan 413

Auraiya Uttar Pradesh 663

Kawas Gujarat 645

Dadri Uttar Pradesh 817

Jhanor-Gandhar Gujarat 648

Kayamkulam Kerala 350

Faridabad Haryana 430

Total (Gas) 3,966


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Introduction of gas power station ntpc(Auraiya)

Auraiya gas power station is a gas based combined cycle power plant of NTPC.

The plant is situated in Distt. Auraiya of Uttar Pradesh, on main railway track. It is

60 km from Kanpur. The plant has 4 Gas Turbines (GT) and 2 Steam Turbines

(ST) with 4 Waste Heat Recovery Boilers (WHRB). Though the plant is normally

operated on combined cycle but it may be operated on open cycle mode in case of

any problem in WHRB. The plant is basically divided in two modules and each

module has 2 GT, 1ST and 2WHRB. Their capacities are as follows:-

MODULE I: Gas Turbine Capacity : 2 X 111.19 MW

Steam Turbine Capacity : 109.3 MW

Total Module I Capacity : 331.68 MW

MODULE II: Gas Turbine Capacity : 2 X 111.19 MW

Steam Turbine Capacity : 109.3 MW


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Total Module II Capacity : 331.68 MW

TOTAL PLANT CAPACITY: 663.36 MW

THE BASIC DIAGRAM OF ARRANGEMENT OF

UNITS IN AURAIYA GAS POWER PLANT

GT - Gas Turbine

STSteam Turbine

WHRBWaste Heat Recovery Boiler

ST # 1 ST # 2

109.3 MW 109.3 MW

111.19 MW 111.19 MW 111.19 MW 111.19 MW

STATION CAPACITY

MODULE #1

2 X 111.19 + 109.3 = 331.68 MW

MODULE #2

2 X 111.19 + 109.3 = 331.68 MW

663.36 MW

GT # 1 GT # 2 GT # 3 GT # 4

WHRB #1 WHRB #2 WHRB #3 WHRB #4


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Combined CYCLE

Combined Cycle is a term used when a power producing engines or plant

employs more than one thermodynamic cycle. Heat engines are only able to use a

portion of the energy their fuel generates (usually less than 30%). The remaining

heat from combustion is generally wasted. Combining two or more cycles such

as the Brayton cycle and Rankine Cycle results in improved overall efficiency.

Combined Cycle Plants

The combined-cycle unit combines the Rankine (steam turbine) and Brayton

(gas turbine) thermodynamic cycles by using heat recovery boilers to capture the

energy in gas turbine exhaust gases for steam production to supply a steam turbine

as shown in the Combined Cycle Cogeneration Unit. Process steam can be also

provided for industrial purposes.

Fossil fuel-fired (central) power plants use either steam or combustion

turbines to provide the mechanical power to electrical generators. Pressurized high

temperature steam or gas expands through various stages of turbines, transferring

energy to the rotating turbine blades. The turbine is mechanically coupled to a

generator, which produces electricity.


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Combined cycle operation of ntpc, Auraiya


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FUELS

Mainly two fuels are used in this gas power plant which are listed below

Natural gas Naphtha

The Natural gas is supplied by GAIL, Dibiyapur and is taken directly

From the pipeline which goes from Hazira to Jagdishpur.

The other fuel is supplied by IOC, Kanpur and Mathura.

STORAGE CAPACITY FOR NAPHTHA

There are two tanks for storing Naphtha fuel each having a capacity of 1500 KL.

There are three transfer pumps for loading fuel from tankers. The two pumps

work and the third is auxiliary. There are twelve unloading pipes, thus twelve

trucks con be unloaded at a time.

If a gas turbine is running at full load then it consumes 20 KL Naphtha fuelin one hour.


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In addition to traditional power generation applications, gas turbines are recently

being employed as power sources for pumps used in emergency situations such as

natural disasters, due to their short start-up times and for water jet propulsion

systems (used in high-speed ships). In thermal power plants using gas turbines,

there is a trend towards the use of combined cycle power generation systems. This

technology takes advantage of the high temperature of the exhaust gases produced

by gas turbines, passing the gases through a heat recovery steam generator to

produce high- temperature steam. This steam is then routed through a steam

turbine to generate additional electricity.

The approach yields a greater thermal efficiency than is possible with a gas turbine

alone, and recently some power plants, including the Higashi-Niigata Thermal

Power Station, have surpassed 50% thermal efficiency. This level of efficiency is

among the worlds best.

As a means of increasing the thermal efficiency of gas turbines themselves,

manufacturers are beginning to build turbines with high inlet temperatures.


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BOILER ECINOMIZER:-

A boiler economizer is a device that reduces the overall fuel requirements aboiler requires which results in reduced fuel costs as well as fewer emissions

since the boiler operates at a much higher efficiency. Boiler economizers recover

the waste heat from the boilers hot stack gas and transfer this waste heat to the

boilers feed-water. Because the boiler feed-water is now at a higher temperature

that it would have been without a boiler economizer, the boiler does not need to

provide as much additional heating to produce the steam requirements of a facility

or process, thereby using less fuel and reducing the fuel expenses. Boiler

economizers also help improve a boilers efficiency by extracting heat from the

flue gases discharged from the final super heater section of a radiant/reheat unit or

the evaporation bank of a non-reheat boiler. Heat is transferred, again, back to the

boiler feed-water, which enters at a much lower temperature than saturated steam.

WASTE HEAT RECOVERY:-Many industrial processes generate large amount of waste energy that simply

pass out of plant stacks and into the atmosphere or are otherwise lost. Most

industrial waste heat streams are liquid, gaseous or a combination of the two and

have temperatures from slightly above ambient to over 2000F.

Waste heat recovery methods used with industrial process heating operations

intercept the waste gases before they leave the process, extract some of the heat

they contain, and recycle that heat back to the process.

Common methods of recovering heat include direct heat recovery to the

process, recuperators/regenerators, and waste heat boilers.


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WATER TREATMENT PLANT & STORAGE

Since steam is taken out continuously and returned to the boiler, losses due toblow downs and leakages have to be made up for maintaining designed boiler

water quantity by means of the level gauges provided on the boiler drum. For this,

continuous make up water is added to the boiler water system. Since this make up

requires pure water this quality water is obtained by a Demineralised (DM) water

treatment plant. However some storage is essential as DM plant may be down for

maintenance. For this purpose a storage tank is installed from which continuously

DM water is drawn for boiler make up.

The impurities in water input to this plant generally consist of calcium andmagnesium salts imparting hardness to the water. These salts have to be removed

from the water. If hardness is present in makeup water to the boiler, the salts not

only form deposits on the tube surfaces but also lead to overheating in those

localities resulting in tube failures. Therefore these have to be completely removed

for use as boiler make up, this is done using DM water treatment plant which gives

the purest form of water.

This generally consists of cation, anion and mixed bed exchangers. The final

water from this process consists generally of hydrogen ions and hydroxide ions

which is the chemical combination of pure water. The DM water being very pure is

highly corrosive, once it absorbs oxygen from the atmosphere because of its very

high affinity for oxygen absorption. The capacity of the DM plant is dictated by the

type and quantity of salts in the raw water input.

The storage tank for DM water is made from materials not affected by corrosive

water, such as PVC. The piping and valves are generally of stainless steel.


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powering massive steam turbines with high temperature steam generated by a

nuclear reactor.

In order to increase the efficiency of steam turbines, Takasago Machinery

Works, Mitsubishi Heavy Industries Ltd is using 3D design technology to shaperotor blades, developing and manufacturing larger rotor blades and designing

methods to prevent the loss of steam throughput.

PASS OUT OR EXTRACTION TURBINES:-

The steam turbines that are used in NTPC, Auraiya are Pass out OR Extraction

turbines. In these types of turbines steam is exhausted at different stages and used

in heating the steam water for the boiler or processing work.

The high pressure steam from the boiler enters the HP stage of turbine where it

expands and the pressure is reduced to such a value that is required for processing

work. A part of this low pressure steam leaving the high pressure stage is suppliedto the processing work while the remaining steam expands further in the L.P. stage.

The exhaust steam from the processing plant and the low pressure turbine steam is

condensed in the condenser and pumped back to the boiler.


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CIRCULATING WATER PUMPS

These pumps are used to pump water to the deaerator from where the watergoes to boiler feed pump.

DEAERATOR

The deareators are used to deaerate the water before feeding it into BFP. This isdone because HRB is a water tube boiler and the tubes containing water have very

small diameter. There are some gases like CO2 if present in water they can create

rusting or can choke the tubes. So these gases are removed in the deaerator. There

are total four deareators in the NTPC, Auraiya one each for every WHRB.

WORKING OF WHRB:-

The feed water enters into steam drum through boiler economizer from where it

goes into boiler and converted into steam. This steam further goes to super heater

and at the output superheated steam at the temperature of 530 C is gained. This

superheated steam is used to drive steam turbine to generate electricity as in the

cycle.


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COOLING SYSTEM

The majority of the electricity generated is produced by steam driven turbinegenerators. A very important step in this power generation process is the

condensation of exhaust steam from the final, low pressure turbine when the steam

condenses, the rapid decrease from vapor-to-liquid specific volume creates a

vacuum at the turbine outlet (monitored as turbine backpressure) that increases

power generation efficiency.

Low turbine backpressures are achieved when the steam condensate

temperatures are lower.

Designing and operating a cooling system that can consistently and continually

remove the heat of condensation at those low temperatures is essential. Therefore,

the cooling system should be considered the integral part of power generation

process that can have a major influence on the overall power plant performance

and availability.

The waste heat removed by the cooling system during the steam condensation

step must ultimately be transferred to the surrounding environment. Having a high

unit heat capacity, water has been the traditional transfer medium of choicebecause it has been readily available, relatively inexpensive and reusable up to a

point. Wet cooling systems use water to absorb heat via indirect contact with steam

in a condenser. The heated water is either discharged to a large surface water body

such as lake or river (once through cooling) or passed through a cooling tower and

recycled back to the condenser (recirculated cooling).

Many of the plants built during the last decade are based on the combined cycle

process of power generation. In the most common 2-on-1 arrangement,

electricity is produced by two combustion turbine generators with the hot exhaustgas from these turbines used to produce steam in a heat recovery steam generator

for a single steam driven turbine generator. Since the combustion turbines produce

roughly two third of the overall electrical power and have no steam condensation

step, a combined cycle plant requires only about one-third the amount of cooling

needed by a conventional steam electric plant of equivalent capacity.


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the fill the water splashes down from one fill to the next by gravity. Outside air

enters the towers via fans in the form of horizontal slats in the side of the towers.

The slates usually slope downward to keep t water in. The intimate mix between

air and water enhances heat and mass transfer (evaporation), which cools the

water. Cold water is then collected in concrete basin at the bottom of the towerwhere it is pumped back to the condenser. The now hot, moist air leaves the tower

at the top.


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WATER SOURCES


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CONTROL SYSTEM OF THE PLANT

There are three of controlling systems available in the plant and they are asfollows:-

LOCAL CONTROL:-In it the control commands are given to the machine from that place where

machine is located. This system is rarely used.

SWITCHYARD CONTROL:-In it all controlling commands are given from switchgear room.

REMOTE SYSTEM:-This system is frequently used. In it all controlling commands are given

from central computerized control room.

In the central computerized control room, there are two set of

controlling devices. If one set is shut down for maintenance then

commands are given by second set.


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ELECTRICAL AND SWITCHYARD

DEPARTMENT

Electrical energy management system ensures supply of energy to every

consumer at all times at rated voltage, frequency and specified waveform at lowest

cost and minimum environmental degradation. The switchgear, protection and

network automation are integral parts of the modern energy management system

and national economy. The modern 3-ph, 50 HZ, AC interconnected system has

several conventional and non-conventional power plants, HV transmission

network, substations, MV and LV distribution systems and connected electrical

loads. The energy form is supplied to various consumers located in vast

geographical area, instantly, automatically, and safely with required quality at all

times. The service continuity and high quality of power supply have become very

important.

For fulfilling the foresaid purpose, a state of the art, scientifically and

technologically advanced SUBSTATION is required. Sub-station is the load

control centre of the thermal plant where power at rated voltage, frequency and

waveform is exported/ imported as per requirements.

The substation at NTPC, Auraiya has two switchyards, one of 220 KV and

other of 440KV. There are two bus bars and one transfer bus for supplyingelectricity. After step up, the 220 KV output from the generator transformer is fed

to either of two bus bars through relays and circuit breakers and these are

connected to various feeders through various equipments.

There are total 10 lines going out of NTPC, Auraiya for supplying

electricity. Their descriptions are as follows:-

1. 2 lines of 220 KV to Agra.2. 2 lines of 440 KV to Agra.3. 2 lines of 220 KV to Maingaon, M.P.4. 2 lines of 220 KV to Railway.5. 2 lines of 220 KV to GAIL, Dibiyapur.


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DIFFERENT TYPES OF EQUIPMENTS USED IN

SUB-STATIONS:-

BUS-BARS:-

Bus bar is term used for main bar of conductor carrying an electric current to

which may be made. These are mainly convenient means of connecting switches

and other equipments into various arrangements.

There are two bus bars and one transfer bus for supplying electricity. Both bus

bars are used continuously and transfer bus is used in case of many repairing or

maintenance.

LIGHTENING ARRESTORS:-

These are equipments designed to protect insulators of power lines and

electrical installations from lightening surges by diverting the surge to earth and

instantly restoring the circuit insulation to its normal strength with respect to earth.

INDICATING AND METERING INSTRUMENTS:-

Ammeters, voltmeters, watt meters, KWH meter and KVA meters are installed

in sub-station to watch over the currents flowing in the circuit and voltages and

power loads.

ISOLATORS:-

One of the cardinal measures for ensuring full safety in carrying out work onequipment in electrical installations is to disconnect reliably the unit or the section

on which the work is to be done from all other live parts of the installation. To

guard against mistakes, it is necessary that apparatus, which make a visible break

in the circuit such as isolators, should do this.


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Isolators do not have arc control devices therefore cannot be used to interrupt

currents at which the arc will be drawn across the contacts. The open arc in these is

very dangerous, in that it will not only damage the isolator or the equipment

surrounding it but will also cause the flashover between the phase in other words, it

will result in short circuit in the installation i.e. why isolators are used only fordisconnecting parts after de-energizing them by opening their respective circuits by

use of their circuit breakers.

CIRCUIT BREAKERS:-

Circuit breakers are mechanical devices designed to close or open contact or

electrical circuit under normal conditions. CB is equipped with a strip coil directly

attached to relay or other means to operate in abnormal conditions such as over

power etc. In NTPC, Auraiya Gas power plant SF6 CB is used.

In sulphur puffer type SF6 CB is filled with SF6 gas at single pressure

(4to6kgf/cm2).

The pressure and gas flow required for arc extinction is obtained by piston

action.

In double pressure type SF6 CB the gas from high-pressure system is released

to into low-pressure system over the arc during the arc quenching process.

DUPLICATE BUS BAR ARRANGEMENT:-

The duplicate bus bar system provides additional flexibility, continuity of

supply and permits periodic maintenance without total shut down. In the event of

fault on one bus the other bus can be used.

RELAYS:-

Relay is a device by means of which an electrical circuit (trip or alarm circuit)

is controlled (closed) by change in the other circuit. Relays are automatic. The

function of relay in power supply system is to recognize a start out and to initiate

the operation of CB or other devices to isolate the defective elements with

minimum disturbance to the normal power supply system.


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CONCLUSION

Thus this vocational training report deals with overall operation of the NTPC plantin Auraiya. Also the report has a view of some parts used in plant.

The depleting resources of oil, gas and coal (the conventional fuels) along

with atmospheric pollution problems have drawn the attention of the scientists and

engineers all over the world to find out other sources for the generation of electric

power. These sources of energy are going to attain the nerve centre of the future

power plants. Though atomic and nuclear power plants have been developed on

conventional lines, but lot of work is yet to be done. Efforts are being made to

convert atomic and nuclear energy directly into electric power with the help of

magneto-hydrodynamic generator and other equipments.

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Final Report - Ntpc

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