NTPC BADARPUR PROJECT REPORT

PROJECT / TRAINING REPORT

( PROJECT / TRAINING SEMESTER JANUARY – JULY )

BTPS,NTPC BADARPUR ,NEW DELHI

A

DISSERTATION SUBMITTED TO

PANJAB UNIVERSITY, CHANDIGARH

SUBMITTED In Partial fulfillment of the

BACHELOR OF ENGINEERING (B.E)

SUBMITTED BY

ARVIND KUMAR NEGI

ROLL NO : SG – 9414

UNDER THE GUIDANCE OF

Mr. JASPAL SINGH Mr. SONIA SINGH

FACULTY COORDINATOR INDUSTRY COORDINATOR

AP EEE DEPARTMENT BTPS,NTPC BADARPUR

PUSSGRC HOSHIARPUR NEW DELHI 110044

INSTITUTE: PANJAB UNIVERSITY SSG REGIONAL CENTER HOSHIARPUR

1

CERTIFICATE

This is to certify that the Internship Report is submitted by ARVIND KUMAR NEGI,

SG9414 in partial fulfillment of the requirements of INTERNSHIP at NTPC Limited,

BADARPUR as part of degree of BACHELOR OF ENGINEERING in Electrical & Electronics

Engineering of PANJAB UNIVERSITY SSG REGIONAL CENTRE, HOSHIARPUR, session

2012-2013 is a record of bonafide work carried out under our supervision and has not be

submitted anywhere else for any other purpose.

(Signature of student)

ARVIND KUMAR NEGI

3 JUNE 2013 SG-9414 , EEE 8TH SEM

Certified that the above statement made by the student is correct to the best of our

knowledge and belief.

Mr. JASPAL SINGH Ms. SONIA SINGH

FACULTY COORDINATOR INDUSTRY COORDINATOR

AP EEE DEPARTMENT BTPS,NTPC BADARPUR ,

PUSSGRC HOSHIARPUR NEW DELHI 110044

2

ACKNOWLEDGEMENT

It has been a great honor and privilege to undergo training at NTPC Limited, Badarpur,

Haryana, India. I am very grateful to Ms. RACHNA SINGH BHAL (DGM HR) & Ms.

SONIA SINGH (DEPUTY MANAGER O&M) for giving their valuable time and

constructive guidance in preparing the internship report for Internship. It would not

have been possible to complete this report in short period of time without their

kind encouragement and valuable guidance.

3 JUNE, 2013 ARVIND KUMAR NEGI

B.E.-8TH Sem(EEE)

2009-13 Batch

3

TABLE OF CONTENT

Table of ContentsCHAPTER-1........................................................................................................................................

COMPANY PROFILE...........................................................................................................................

VISION AND MISSION........................................................................................................................

Core Values – BE COMMITTED..........................................................................................................

POWER GENERATION IN INDIA.........................................................................................................

EVOLUTION.......................................................................................................................................

STRATEGIES.......................................................................................................................................

NTPC HEADQUARTERS......................................................................................................................

NTPC PLANTS....................................................................................................................................

FUTURE GOALS..................................................................................................................................

POWER BURDEN...............................................................................................................................

ENVIRONMENT POLICY & ENVIRONMENT MANAGEMENT SYSTEM.................................................

NATIONAL ENVIRONMENT POLICY....................................................................................................

NTPC ENVIRONMENT POLICY............................................................................................................

ENVIRONMET MANAGEMENT, OCCUPATIONAL HEALTH and SAFETY SYSTEMS...............................

POLLUTION CONTROL SYSTEMS........................................................................................................

UP GRADATION & RETROFITTING of POLLUTION CONTROL SYSTEMS..............................................

OVERALL POWER GENERATION........................................................................................................

NTPC INTERNATIONAL CELL..............................................................................................................

CHAPTER-2........................................................................................................................................

ABOUT BADARPUR THERMAL POWER STATION...............................................................................

BADARPUR THERMAL POWER STATION............................................................................................

FROM COAL TO ELECTRICITY PROCESS..............................................................................................

MAIN GENERATOR............................................................................................................................

MAIN TURBINE DATA........................................................................................................................

OPERATION.......................................................................................................................................

CHAPTER-3........................................................................................................................................

EMD- I...............................................................................................................................................

HT/LT MOTORS TURBINE & BOILER SIDE..........................................................................................

COAL HANDLING PLANT (C.H.P) & NEW COAL HANDLING PLANT (N.C.H.P).....................................

4

CHAPTER-3........................................................................................................................................

EMD II................................................................................................................................................

Generator and Auxiliaries.................................................................................................................

Transformer......................................................................................................................................

CHAPTER-4........................................................................................................................................

CONTROL AND INSTRUMENTATION..................................................................................................

INTRODUCTION.................................................................................................................................

OBJECTIVE........................................................................................................................................

MAIN OUTLINE..................................................................................................................................

BLOCK DIAGRAM...............................................................................................................................

DISCRIPTION OF BLOCK DIAGRAM....................................................................................................

CIRCUIT DISCRIPTION OF AUTO MODE.............................................................................................

CIRCUIT DIAGRAM FOR SET POINT....................................................................................................

CIRCUIT DIAGRAM FOR VARIABLE INPUT..........................................................................................

I-06R MINI CARD CIRCUIT DIAGRAM.................................................................................................

TRIGGER CIRCUIT..............................................................................................................................

ELECTRICAL ACTUATOR CIRCUIT.......................................................................................................

DEXTILE, LIMIT SWITCH AND RELAY PIN DIAGRAM..........................................................................

COMPONENT DISCRIPTION...............................................................................................................

LIMIT SWITCH....................................................................................................................................

RELAY................................................................................................................................................

CONTACTOR RELAY...........................................................................................................................

7805 VOLTAGE REGULATOR IC..........................................................................................................

2N3055 TRANSISTOR.........................................................................................................................

LIGHT EMITTING DIODE....................................................................................................................

ZENER DIODE.....................................................................................................................................

POTENTIOMETER..............................................................................................................................

555 TIMER IC.....................................................................................................................................

CAPACITOR .......................................................................................................................................

RESISTOR……………………………………………………………………………………………………………………………………….

SINGLE PHASE AC MOTOR………………………………………………………………………………………………………..

5

CHAPTER-1

COMPANY PROFILE

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 FIIs,

Domestic Banks, Public and others hold the balance 10.5%. Within a span of 31 years,

NTPC has emerged as a truly national power company, with power generating facilities

in all the major regions of the country.

VISION AND MISSIONVision“To be the world’s largest and best power producer, powering India’s growth.” Mission“Develop and provide reliable power, related products and services at competitive prices,

integrating multiple energy sources with innovative and eco-friendly technologies and

contribute to society.”

Core Values – BE COMMITTED

B Business Ethics

E Environmentally & Economically Sustainable

C Customer Focus

O Organizational & Professional Pride

M Mutual Respect & Trust

M Motivating Self & others

I Innovation & Speed

T Total Quality for Excellence

T Transparent & Respected Organization

6

E Enterprising

D Devoted

Figure 1: NTPC OPERATION GRAPH

POWER GENERATION IN INDIANTPC’s core business is engineering, construction and operation of power generating

plants. It also provides consultancy in the area of power plant constructions and power

generation to companies in India and abroad. As on date the installed capacity of NTPC

is 27,904 MW through its 15 coal based (22,895 MW), 7 gas based (3,955 MW) and 4

Joint Venture Projects (1,054 MW). NTPC acquired 50% equity of the SAIL Power Supply

Corporation Ltd. (SPSCL). This JV Company operates the captive power plants of

Durgapur (120 MW), Rourkela (120 MW) and Bhilai (74 MW). NTPC also has 28.33%

stake in Ratnagiri Gas & Power Private Limited (RGPPL) a joint venture company

between NTPC, GAIL, Indian Financial Institutions and Maharashtra SEB Co Ltd.

7

Figure 2: TOTAL POWER GENERATION

NTPC has set new benchmarks for the power industry both in the area of power plant

construction and operations. Its providing power at the cheapest average tariff in the

country..

NTPC is committed to the environment, generating power at minimal environmental

cost and preserving the ecology in the vicinity of the plants. NTPC has undertaken

massive a forestation in the vicinity of its plants. Plantations have increased forest area

and reduced barren land. The massive a forestation by NTPC in and around its

Ramagundam Power station (2600 MW) have contributed reducing the temperature in

the areas by about 3°c. NTPC has also taken proactive steps for ash utilization. In 1991, it

set up Ash Utilization Division

A "Centre for Power Efficiency and Environment Protection (CENPEEP)" has been

established in NTPC with the assistance of United States Agency for International

Development (USAID). Cenpeep is efficiency oriented, eco-friendly and eco-nurturing

8

initiative - a symbol of NTPC's concern towards environmental protection and continued

commitment to sustainable power development in India.

As a responsible corporate citizen, NTPC is making constant efforts to improve the socio-

economic status of the people affected by its projects. Through its Rehabilitation and

Resettlement programmes, the company endeavors to improve the overall socio

economic status Project Affected Persons.

NTPC was among the first Public Sector Enterprises to enter into a Memorandum of

Understanding (MOU) with the Government in 1987-88. NTPC has been placed under

the 'Excellent category' (the best category) every year since the MOU system became

operative.

Harmony between man and environment is the essence of healthy life and growth.

Therefore, maintenance of ecological balance and a pristine environment has been of

utmost importance to NTPC. It has been taking various measures discussed below for

mitigation of environment pollution due to power generation.

EVOLUTION

NTPC was set up in 1975 in 100% by the ownership of Government

of India. In the last 30 years NTPC has grown into the largest power

utility in India.

In 1997, Government of India granted NTPC status of ‘Navratna’

being one of the nine jewels of India, enhancing the powers to the

Board of directors.

9

19751975

19971997

NTPC became a listed company with majority Government

ownership of 89.5%. NTPC becomes third largest by market

capitalisation of listed companies.

The company rechristened as NTPC Limited in line with its

changing business portfolio and transforms itself from a thermal

power utility to an integrated power utility.

National Thermal Power Corporation is the largest power

generation company in India. Forbes Global 2000 for 2008 ranked

it 411th the world.

National Thermal Power Corporation is the largest power

generation company in India. Forbes Global 2000 for 2008 ranked

it 317th in the world.

NTPC has also set up a plan to achieve a target of 50,000 MW

generation capacities.

NTPC has embarked on plans to become a 75,000 MW company

by 2017.

10

20042004

20052005

20082008

20092009

20122012

20172017

NTPC is the largest power utility in India, accounting for about 20% of India’s installed

capacity.

STRATEGIES

Figure 3: NTPC STRATEGIES

NTPC HEADQUARTERS

NTPC Limited is divided in 8 HeadquartersS. NO. HEADQUARTERS CITY

1. NCRHQ DELHI

2. ER HEADQUARTER-1 BHUBANESHWAR

3. ER HEADQUARTER-2 PATNA

4. NRHQ LUCKNOW

5. SR HEADQUARTER HYDERABAD

6. WR-1 HEADQUARTER MUMBAI

7. HYDRO HEADQUARTER DELHI

8. WR-2 HEADQUARTER RAIPUR

NTPC PLANTS1. Thermal-Coal based

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S. NO. CITY STATE INSTALLED

CAPACITY(MW)

1. SINGRAULI UTTAR PRADESH 2000

2. KORBA CHATTISGHAR 2600

3. RAMAGUNDAM ANDHRA PRADESH 2600

4. FARAKKA WEST BENGAL 2100

5. VINDHYACHAL MADHYA PRADESH 3260

6. RIHAND UTTAR PRADESH 2500

7. KAHALGAON BIHAR 2300

8. DADRI UTTAR PRADESH 1820

9. TALCHER ORISSA 3000

10. UNCHAHAR UTTAR PRADESH 1050

11. TALCHER ORISSA 460

12. SIMHADRI ANDHRA PRADESH 1500

13. TANDA UTTAR PRADESH 440

14. BADARPUR DELHI 705

15. SIPAT CHHATTISGHAR 2320

16. SIPAT CHHATTISGHAR 1980

17. BONGAIGAON ASSAM 750

18. MOUDA MAHARASHTRA 1000(2*500MW)

19. RIHAND UTTAR PRADESH 2*500MW

20. BARH BIHAR 3300(5*660)

TOTAL 31495MW

2. COAL BASED (Owned by JVs)

S.NO. NAME OF THE CITY STATE INSTALLED

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JV CAPACITY(MW)

1. NSPCL DURGAPUR WEST BENGAL 120

2. NSPCL ROURKELA ORISSA 120

3. NSPCL BHILAI CHHATTISGHAR 574

4. NPGC AURANGABAD BIHAR 1980

5. M.T.P.S. KANTI BIHAR 110

6. BRBCL NABINAGAR BIHAR 1000

TOTAL 3904MW

3. GAS Based

S.NO. CITY STATE INSTALLED

CAPACITY(MW)

1. ANTA RAJSTHAN 419

2. AURAIYA UTTAR PRADESH 652

3. KAWAS GUJARAT 645

4. DADRI UTTAR PRADESH 817

5. JHANOR GUJARAT 648

6. KAYAMKULAM KERALA 350

7. FARIDABAD HARYANA 430

TOTAL 3995MW

NTPC HYDEL

13

The company has also stepped up its hydroelectric power (hydel) projects

implementation. Currently the company is mainly interested in the North-east India

wherein the Ministry of Power in India has projected a hydel power feasibility of 3000

MW.

There are few run of the river hydro projects are under construction on tributory of the

Ganges. In which three are being made by NTPC Limited. These are:

Loharinag Pala Hydro Power Project by NTPC Ltd: In Loharinag Pala Hydro Power Project

with a capacity of 600 MW (150 MW x 4 Units). The main package has been awarded.

The present executives' strength is 100+. The project is located on river Bhagirathi (a

tributory of the Ganges) in Uttarkashi district of Uttarakhand state. This is the first

project downstream from the origin of the Ganges at Gangotri(Project has been

discontinued by GoI).

Tapovan Vishnugad 520MW Hydro Power Project by NTPC Ltd: In Joshimath town.#Lata

Tapovan 130MW Hydro Power Project by NTPC Ltd: is further upstream to Joshimath

(under environmental revision) Koldam Hydro Power Project 800 MW in Himachal

Pradesh (130 km from Chandigarh)Amochu in Bhutan Rupasiyabagar Khasiabara HPP,

261 MW in Pithoragarh,uttarakhand State, near China Border.

FUTURE GOALSThe company has also set a serious goal of having 50000 MW of installed capacity by

2012 and 75000 MW by 2017. The company has taken many steps like step-up its

recruitment, reviewing feasibilities of various sites for project implementations etc. and

has been quite successful till date. NTPC will invest about Rs 20,000 crore to set up a

3,900-megawatt (MW) coal-based power project in Madhya Pradesh. Company will also

start coal production from its captive mine in Jharkhand in 2011–12, for which the

company will be investing about 18 billion. ALSTOM would be a part of its 660-MW

supercritical projects for Solapur II and Mouda II in Maharashtra.ALSTOM would execute

turnkey station control and instrumentation (C&I) for this project.

14

POWER BURDENIndia, as a developing country is characterized by increase in demand for electricity and

as of moment the power plants are able to meet only about 60–75% of this demand on

an yearly average. The only way to meet the requirement completely is to achieve a rate

of power capacity addition (implementing power projects) higher than the rate of

demand addition. NTPC strives to achieve this and undoubtedly leads in sharing this

burden on the country.

ENVIRONMENT POLICY & ENVIRONMENT MANAGEMENT SYSTEMDriven by its commitment for sustainable growth of power, NTPC has evolved a well

defined environment management policy and sound environment practices for

minimizing environmental impact arising out of setting up of power plants and

preserving the natural ecology.

NATIONAL ENVIRONMENT POLICY At the national level, the Ministry of Environment and Forests had prepared a draft

Environment Policy (NEP) and the Ministry of Power along with NTPC actively

participated in the deliberations of the draft NEP. The NEP 2006 has since been

approved by the Union Cabinet in May 2006.

NTPC ENVIRONMENT POLICY As early as in November 1995, NTPC brought out a comprehensive document entitled

"NTPC Environment Policy and Environment Management System". Amongst the guiding

principles adopted in the document are company's proactive approach to environment,

optimum utilization of equipment, adoption of latest technologies and continual

15

environment improvement. The policy also envisages efficient utilization of resources,

thereby minimizing waste, maximizing ash utilization and providing green belt all around

the plant for maintaining ecological balance.

ENVIRONMET MANAGEMENT, OCCUPATIONAL HEALTH and SAFETY SYSTEMS NTPC has actively gone for adoption of best international practices on environment,

occupational health and safety areas. The organization has pursued the Environmental

Management System (EMS) ISO 14001 and the Occupational Health and Safety

Assessment System OHSAS 18001 at its different establishments. As a result of pursuing

these practices, all NTPC power stations have been certified for ISO 14001 & OHSAS

18001 by reputed national and international Certifying Agencies.

POLLUTION CONTROL SYSTEMSWhile deciding the appropriate technology for its projects, NTPC integrates many

environmental provisions into the plant design. In order to ensure that NTPC comply

with all the stipulated environment norms, various state-of-the-art pollution control

systems / devices as discussed below have been installed to control air and water

pollution.

Electrostatic Precipitators

The ash left behind after combustion of coal is arrested in high efficiency Electrostatic

Precipitators (ESP’s) and particulate emission is controlled well within the stipulated

norms. The ash collected in the ESP’s is disposed to Ash Ponds in slurry form.

Flue Gas Stacks

16

Tall Flue Gas Stacks have been provided for wide dispersion of the gaseous emissions

(SOX, NOX etc) into the atmosphere.

Low-NOX Burners

In gas based NTPC power stations, NOx emissions are controlled by provision of Low-

NOx Burners (dry or wet type) and in coal fired stations, by adopting best combustion

practices.

Neutralization Pits

Neutralization pits have been provided in the Water Treatment Plant (WTP) for pH

correction of the effluents before discharge into Effluent Treatment Plant (ETP) for

further treatment and use.

Coal Settling Pits / Oil Settling Pits

In these Pits, coal dust and oil are removed from the effluents emanating from the Coal

Handling Plant (CHP), coal yard and Fuel Oil Handling areas before discharge into ETP.

DE & DS Systems

Dust Extraction (DE) and Dust Suppression (DS) systems have been installed in all coal

fired power stations in NTPC to contain and extract the fugitive dust released in the Coal

Handling Plant (CHP).

Cooling Towers

Cooling Towers have been provided for cooling the hot Condenser cooling water in

closed cycle Condenser Cooling Water (CCW) Systems. This helps in reduction in thermal

pollution and conservation of fresh water.

Ash Dykes & Ash Disposal systems

17

Ash ponds have been provided at all coal based stations except Dadri where Dry Ash

Disposal System has been provided. Ash Ponds have been divided into lagoons and

provided with garlanding arrangements for change over of the ash slurry feed points for

even filling of the pond and for effective settlement of the ash particles.

Ash in slurry form is discharged into the lagoons where ash particles get settled from the

slurry and clear effluent water is discharged from the ash pond. The discharged effluents

conform to standards specified by CPCB and the same is regularly monitored.

At its Dadri Power Station, NTPC has set up a unique system for dry ash collection and

disposal facility with Ash Mound formation. This has been envisaged for the first time in

Asia which has resulted in progressive development of green belt besides far less

requirement of land and less water requirement as compared to the wet ash disposal

system.

Ash Water Recycling System

Further, in a number of NTPC stations, as a proactive measure, Ash Water Recycling

System (AWRS) has been provided. In the AWRS, the effluent from ash pond is circulated

back to the station for further ash sluicing to the ash pond. This helps in savings of fresh

water requirements for transportation of ash from the plant.

The ash water recycling system has already been installed and is in operation at

Ramagundam, Simhadri, Rihand, Talcher Kaniha, Talcher Thermal, Kahalgaon, Korba and

Vindhyachal. The scheme has helped stations to save huge quantity of fresh water

required as make-up water for disposal of ash.

Dry Ash Extraction System (DAES)

Dry ash has much higher utilization potential in ash-based products (such as bricks,

aerated autoclaved concrete blocks, concrete, Portland pozzolana cement, etc.). DAES

has been installed at Unchahar, Dadri, Simhadri, Ramagundam, Singrauli, Kahalgaon,

Farakka, Talcher Thermal, Korba, Vindhyachal, Talcher Kaniha and BTPS.

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Liquid Waste Treatment Plants & Management System

The objective of industrial liquid effluent treatment plant (ETP) is to discharge lesser and

cleaner effluent from the power plants to meet environmental regulations. After primary

treatment at the source of their generation, the effluents are sent to the ETP for further

treatment. The composite liquid effluent treatment plant has been designed to treat all

liquid effluents which originate within the power station e.g. Water Treatment Plant

(WTP), Condensate Polishing Unit (CPU) effluent, Coal Handling Plant (CHP) effluent,

floor washings, service water drains etc. The scheme involves collection of various

effluents and their appropriate treatment centrally and re-circulation of the treated

effluent for various plant uses.

NTPC has implemented such systems in a number of its power stations such as

Ramagundam, Simhadri, Kayamkulam, Singrauli, Rihand, Vindhyachal, Korba, Jhanor

Gandhar, Faridabad, Farakka, Kahalgaon and Talcher Kaniha. These plants have helped

to control quality and quantity of the effluents discharged from the stations.

Sewage Treatment Plants & Facilities

Sewage Treatment Plants (STPs) sewage treatment facilities have been provided at all

NTPC stations to take care of Sewage Effluent from Plant and township areas. In a

number of NTPC projects modern type STPs with Clarifloculators, Mechanical Agitators,

sludge drying beds, Gas Collection Chambers etc have been provided to improve the

effluent quality. The effluent quality is monitored regularly and treated effluent

conforming to the prescribed limit is discharged from the station. At several stations,

treated effluents of STPs are being used for horticulture purpose.

Environmental Institutional Set-up

19

Realizing the importance of protection of the environment with speedy development of

the power sector, the company has constituted different groups at project, regional and

Corporate Centre level to carry out specific environment related functions. The

Environment Management Group, Ash Utilisation Group and Centre for Power Efficiency

& Environment Protection (CENPEEP) function from the Corporate Centre and initiate

measures to mitigate the impact of power project implementation on the environment

and preserve ecology in the vicinity of the projects. Environment Management and Ash

Utilisation Groups established at each station, look after various environmental issues of

the individual station.

Environment Reviews

To maintain constant vigil on environmental compliance, Environmental Reviews are

carried out at all operating stations and remedial measures have been taken wherever

necessary. As a feedback and follow-up of these Environmental Reviews, a number of

retrofit and up-gradation measures have been undertaken at different stations.

Such periodic Environmental Reviews and extensive monitoring of the facilities carried

out at all stations have helped in compliance with the environmental norms and timely

renewal of the Air and Water Consents.

UP GRADATION & RETROFITTING of POLLUTION CONTROL SYSTEMSWaste Management

Various types of wastes such as Municipal or domestic wastes, hazardous wastes, Bio-

Medical wastes get generated in power plant areas, plant hospital and the townships of

projects. The wastes generated are a number of solid and hazardous wastes like used

oils & waste oils, grease, lead acid batteries, other lead bearing wastes (such as garkets

etc.), oil & clarifier sludge, used resin, used photo-chemicals, asbestos packing, e-waste,

metal scrap, C&I wastes, electricial scrap, empty cylinders (refillable), paper, rubber

products, canteen (bio-degradable) wastes, buidling material wastes, silica gel, glass

wool, fused lamps & tubes, fire resistant fluids etc. These wastes fall either under

20

hazardous wastes category or non-hazardous wastes category as per classification given

in Government of India’s notification on Hazardous Wastes (Management and Handling)

Rules 1989 (as amended on 06.01.2000 & 20.05.2003). Handling and management of

these wastes in NTPC stations have been discussed below.

Advanced / Eco-friendly Technologies

NTPC has gained expertise in operation and management of 200 MW and 500 MW Units

installed at different Stations all over the country and is looking ahead for higher

capacity Unit sizes with super critical steam parameters for higher efficiencies and for

associated environmental gains. At Sipat, higher capacity Units of size of 660 MW and

advanced Steam Generators employing super critical steam parameters have already

been implemented as a green field project.

Higher efficiency Combined Cycle Gas Power Plants are already under operation at all

gas-based power projects in NTPC. Advanced clean coal technologies such as Integrated

Gasification Combined Cycle (IGCC) have higher efficiencies of the order of 45% as

compared to about 38% for conventional plants. NTPC has initiated a techno-economic

study under USDOE / USAID for setting up a commercial scale demonstration power

plant by using IGCC technology. These plants can use low-grade coals and have higher

efficiency as compared to conventional plants.

With the massive expansion of power generation, there is also growing awareness

among all concerned to keep the pollution under control and preserve the health and

quality of the natural environment in the vicinity of the power stations. NTPC is

committed to provide affordable and sustainable power in increasingly larger quantity.

NTPC is conscious of its role in the national endeavour of mitigating energy poverty,

heralding economic prosperity and thereby contributing towards India’s emergence as a

major global economy.

21

OVERALL POWER GENERATIONUNIT 1997-98 2006-07 % OF

INCREASE

INSTALLED CAPACITY MW 16,847 26,350 56.40

GENERATION MUs 97,609 1,88,674 93.29

NO. OF EMPLOYEES NO. 23,585 24,375 3.34

GENERATION/EMPLOYEE MUs 4.14 7.74 86.95

The table below shows the detailed operational performance of coal based stations over

the years.

Operational Performance of Coal Based NTPC Stations

UNIT 97-

98

98-

99

99-

00

00-

01

01-

02

02-03 03-04 04-05 05-06 06-07

GENERATIO

N BU

106.

2

109.

5

118.

7

130.

1

133.

2

140.8

6

149.1

6

159.1

1

170.8

8

188.6

7

PL % 75.2

0

76.6

0

80.3

9

81.8

0

81.1

0

83.60 84.40 87.51 87.54 89.43

AVAILABILIT

Y FACTOR

85.0

3

89.3

6

90.0

6

88.5

4

81.8

0

88.70 88.80 91.20 89.91 90.09

22

CHAPTER-2

ABOUT BADARPUR THERMAL POWER STATION

Badarpur Thermal Power Station is located at Badarpur area in NCT Delhi. The power

plant is one of the coal based power plants of NTPC. The National Power Training

Institute (NPTI) for North India Region under Ministry of Power, Government of India

was established at Badarpur in 1974, within the Badarpur Thermal power plant (BTPS)

complex.

It is situated in south east corner of Delhi on Mathura Road near Faridabad. It was the

first central sector power plant conceived in India, in 1965. It was originally conceived to

provide power to neighbouring states of Haryana, Punjab, Jammu and Kashmir,U.P.,

Rajasthan, and Delhi.But since year 1987 Delhi has become its sole beneficiary.

BADARPUR THERMAL POWER STATIONCOUNTRY INDIA

LOCATION MATHURA ROAD, BADARPUR, NEW DELHI

STATUS ACTIVE

COMISSION DATE 1973

OPERATOR(S) NTPC

POWER STATION INFORMATION

PRIMARY FUEL COAL-FIRED

GENERATION UNITS 5

POWER GENERATION INFORMATION

INSTALLED CAPACITY 705.00 MW

23

FROM COAL TO ELECTRICITY PROCESS

Figure 4: FLOW CHART of COAL TO ELECTRICITY

Coal to Steam

Coal from the coal wagons is unloaded in the coal handling plant. This Coal is

transported up to the raw coal bunkers with the help of belt conveyors. Coal is

transported to Bowl mills by Coal Feeders. The coal is pulverized in the Bowl Mill,

where it is ground to powder form. The mill consists of a round metallic table on

which coal particles fall. This table is rotated with the help of a motor. There are

three large steel rollers, which are spaced 120 apart. When there is no coal, these

rollers do not rotate but when the coal is fed to the table it pack up between roller

and the table and ths forces the rollers to rotate. Coal is crushed by the crushing

action between the rollers and the rotating table. This crushed coal is taken away to

the furnace through coal pipes with the help of hot and cold air mixture from P.A. Fan.

P.A. Fan takes atmospheric air, a part of which is sent to Air-Preheaters for heating

while a part goes directly to the mill for temperature control. Atmospheric air from

F.D. Fan is heated in the air heaters and sent to the furnace as combustion air.

Water from the boiler feed pump passes through economizer and reaches the

boiler drum. Water from the drum passes through down comers and goes to the

24

bottom ring header. Water from the bottom ring header is divided to all the four

sides of the furnace. Due to heat and density difference, the water rises up in the

water wall tubes. Water is partly converted to steam as it rises up in the furnace.

This steam and water mixture is again taken to thee boiler drum where the steam is

separated from water.

Figure 5: TYPICAL DIAGRAM OF COAL BASED THERMAL POWER PLANT

Water follows the same path while the steam is sent to superheaters for

superheating. The superheaters are located inside the furnace and the steam is

superheated (540 oC) and finally it goes to the turbine.

Flue gases from the furnace are extracted by induced draft fan, which maintains

balance draft in the furnace (-5 to –10 mm of wcl) with forced draft fan. These flue

gases emit their heat energy to various super heaters in the pent house and finally

pass through air-preheaters and goes to electrostatic precipitators where the ash

particles are extracted. Electrostatic Precipitator consists of metal plates, which

are electrically charged. Ash particles are attracted on to these plates, so that

they do not pass through the chimney to pollute t he atmosphere. Regular

mechanical hammer blows cause the accumulation of ash to fall to the bottom of the

precipitator where they are collected in a hopper for disposal.

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Steam to Mechanical Power

From the boiler, a steam pipe conveys steam to the turbine through a stop valve

(which can be used to shut-off the steam in case of emergency) and through control

valves that automatically regulate the supply of steam to the turbine. Stop valve and

control valves are located in a steam chest and a governor, driven from the main

turbine shaft, operates the control valves to regulate the amount of steam used.

(This depends upon the speed of the turbine and the amount of electricity required

from the generator).

Steam from the control valves enters the high pressure cylinder of the turbine, where

it passes through a ring of stationary blades fixed to the cylinder wall. These act as

nozzles and direct the steam into a second ring of moving blades mounted on a disc

secured to the turbine shaft. The second ring turns the shafts as a result of the force

of steam. The stationary and moving blades together constitute a „stage‟ of turbine

and in practice many stages are necessary, so that the cylinder contains a number of

rings of stationary blades with rings of moving blades arranged between them. The

steam passes through each stage in turn until it reaches the end of the high-pressure

cylinder and in its passage some of its heat energy is changed into mechanical

energy.

The steam leaving the high pressure cylinder goes back to the boiler for reheating and

returns by a further pipe to the intermediate pressure cylinder. Here it passes

through another series of stationary and moving blades.

Finally, the steam is taken to the low-pressure cylinders, each of which enters at the

centre flowing outwards in opposite directions through the rows of turbine blades

through an arrangement called the „double flow‟- to the extremities of the cylinder.

As the steam gives up its heat energy to drive the turbine, its temperature and

pressure fall and it expands. Because of this expansion the blades are much larger

and longer towards the low pressure ends of the turbine.

Mechanical Power to Electrical Power

26

As the blades of turbine rotate, the shaft of the generator, which is coupled to

tha of t he turbine, also rotates. It results in rotation of the coil of the generator,

which causes induced electricity to be produced.

Basic Power Plant Cycle

Figure 6: COMPONENTS OF A COAL FIRED THERMAL PLANT

The thermal (steam) power plant uses a dual (vapour+ liquid) phase cycle. It is a

close cycle to enable the working fluid (water) to be used again and again. The

cycle used is Rankine Cycle modified to include superheating of steam, regenerative

feed water heating and reheating of steam. On large turbines, it becomes

economical to increase the cycle efficiency by using reheat, which is a way of

partially overcoming temperature limitations. By returning partially expanded steam,

to a reheat, the average temperature at which the heat is added, is increased and, by

expanding this reheated steam to the remaining stages of the turbine, the exhaust

wetness is considerably less than it would otherwise be conversely, if the maximum

tolerable wetness is allowed, the initial pressure of the steam can be appreciably

increased.

Bleed Steam Extraction: For regenerative system, nos. of non-regulated extractions is

taken from HP, IP turbine. Regenerative heating of the boiler feed water is widely

used in modern power plants; the effect being to increase the average temperature

at which heat is added to the cycle, thus improving the cycle efficiency.

27

On large turbines, it becomes economical to increase the cycle efficiency by using

reheat, which is a way of partially overcoming temperature limitations. By returning

partially expanded steam, to a reheat, the average temperature at which the heat is

added, is increased and, by expanding this reheated steam to the remaining stages

of the turbine, the exhaust wetness is considerably less than it would otherwise be

conversely, if the maximum tolerable wetness is allowed, the initial pressure of the

steam can be appreciably increased.

Bleed Steam Extraction: For regenerative system, nos. of non-regulated extractions is

taken from HP, IP turbine. Regenerative heating of the boiler feed water is widely

used in modern power plants; the effect being to increase the average temperature

at which heat is added to the cycle, thus improving the cycle efficiency.

Figure 7: INTSALLED CAPACITY OF NTPC, BADARPUR

MAIN GENERATOR Maximum continuous KVA rating 24700KVA

Maximum continuous KW 210000KW

Rated terminal voltage 15750V

Rated Stator current 9050 A

Rated Power Factor 0.85 lag

Excitation current at MCR Condition 2600 A

Slip-ring Voltage at MCR Condition 310 V

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Rated Speed 3000 rpm

Rated Frequency 50 Hz

Short circuit ratio 0.49

Efficiency at MCR Condition 98.4%

Direction of rotation viewed Anti Clockwise

Phase Connection Double Star

Number of terminals brought out 9(6 neutral and 3 phases)

MAIN TURBINE DATARated output of Turbine 210 MW

Rated speed of turbine 3000 rpm

Rated pressure of steam before emergency 130 kg/cm^2

Stop valve rated live steam temperature 535 o Celsius

Rated steam temperature after reheat at inlet to receptor valve 535 o Celsius

Steam flow at valve wide open condition 670 tons/hour

Rated quantity of circulating water through condenser 27000 cm/hour

1. For cooling water temperature (o Celsius) 24,27,30,33

2. Steam flow required for 210 MW in ton/hour 68,645,652,662

3. Rated pressure at exhaust of LP turbine in mm of Hg 19.9,55.5,65.4,67.7

OPERATIONTHERMAL POWER PLANT

A Thermal Power Station comprises all of the equipment and a subsystem required to

produce electricity by using a steam generating boiler fired with fossil fuels or befouls to

drive an electrical generator. Some prefer to use the term ENERGY CENTER because such

facilities convert forms of energy, like nuclear energy, gravitational potential energy or

heat energy (derived from the combustion of fuel) into electrical energy. However,

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POWER PLANT is the most common term in the united state; While POWER STATION

prevails in many Commonwealth countries and especially in the United Kingdom.

Such power stations are most usually constructed on a very large scale and designed for

continuous operation.

Typical elements of a coal fired thermal power station

1. Cooling water pump

2. Three -phase transmission line

3. Step up transformer

4. Electrical Generator

5. Low pressure steam

6. Boiler feed water pump

7. Surface condenser

8. Intermediate pressure steam turbine

9. Steam control valve

10. High pressure steam turbine

11. Deaerator Feed water heater

12. Coal conveyor

13. Coal hopper

14. Coal pulverizer

15. Boiler steam drum

16. Bottom ash hoper

17. Super heater

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18. Forced draught (draft) fan

19. Reheater

20. Combustion air intake

21. Economizer

22. Air preheater

23. Precipitator

24. Induced draught (draft) fan

25. Fuel gas stack

The description of some of the components written above is described as follows:

1. Cooling towers

Cooling Towers are evaporative coolers used for cooling water or other working medium

to near the ambivalent web-bulb air temperature. Cooling towers use evaporation of

water to reject heat from processes such as cooling the circulating water used in oil

refineries, Chemical plants, power plants and building cooling, for example. The tower

vary in size from small roof-top units to very large hyperboloid structures that can be up

to 200 meters tall and 100 meters in diameter, or rectangular structure that can be over

40 meters tall and 80 meters long. Smaller towers are normally factory built, while larger

ones are constructed on site.

The primary use of large, industrial cooling tower system is to remove the heat absorbed

in the circulating cooling water systems used in power plants, petroleum refineries,

petrochemical and chemical plants, natural gas processing plants and other industrial

facilities. The absorbed heat is rejected to the atmosphere by the evaporation of some

of the cooling water in mechanical forced-draft or induced draft towers or in natural

draft hyperbolic shaped cooling towers as seen at most nuclear power plants.

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2. Three phase transmission line

Three phase electric power is a common method of electric power transmission. It is a

type of polyphase system mainly used to power motors and many other devices. A

Three phase system uses less conductor material to transmit electric power than

equivalent single phase, two phase, or direct current system at the same voltage. In a

three phase system, three circuits reach their instantaneous peak values at different

times. Taking one conductor as the reference, the other two current are delayed in time

by one-third and two-third of one cycle of the electrical current. This delay between

“phases” has the effect of giving constant power transfer over each cycle of the current

and also makes it possible to produce a rotating magnetic field in an electric motor.

At the power station, an electric generator converts mechanical power into a set of

electric currents, one from each electromagnetic coil or winding of the generator. The

current are sinusoidal functions of time, all at the same frequency but offset in time to

give different phases. In a three phase system the phases are spaced equally, giving a

phase separation of one-third one cycle. Generators output at a voltage that ranges

from hundreds of volts to 30,000 volts. At the power station, transformers: step-up” this

voltage to one more suitable for transmission.

After numerous further conversions in the transmission and distribution network the

power is finally transformed to the standard mains voltage (i.e. the “household”

voltage).

The power may already have been split into single phase at this point or it may still be

three phase. Where the step-down is 3 phase, the output of this transformer is usually

star connected with the standard mains voltage being the phase-neutral voltage.

Another system commonly seen in North America is to have a delta connected

secondary with a center tap on one of the windings supplying the ground and neutral.

This allows for 240 V three phase as well as three different single phase voltages( 120 V

between two of the phases and neutral , 208 V between the third phase ( known as a

wild leg) and neutral and 240 V between any two phase) to be available from the same

supply.

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3. Electrical generator

An Electrical generator is a device that converts kinetic energy to electrical energy,

generally using electromagnetic induction. The task of converting the electrical energy

into mechanical energy is accomplished by using a motor. The source of mechanical

energy may be a reciprocating or turbine steam engine, , water falling through the

turbine are made in a variety of sizes ranging from small 1 hp (0.75 kW) units (rare) used

as mechanical drives for pumps, compressors and other shaft driven equipment , to

2,000,000 hp(1,500,000 kW) turbines used to generate electricity. There are several

classifications for modern steam turbines.

Steam turbines are used in all of our major coal fired power stations to drive the

generators or alternators, which produce electricity. The turbines themselves are driven

by steam generated in ‘Boilers’ or ‘steam generators’ as they are sometimes called.

Electrical power stations use large steam turbines driving electric generators to produce

most (about 86%) of the world’s electricity. These centralized stations are of two types:

fossil fuel power plants and nuclear power plants. The turbines used for electric power

generation are most often directly coupled to their-generators .As the generators must

rotate at constant synchronous speeds according to the frequency of the electric power

system, the most common speeds are 3000 r/min for 50 Hz systems, and 3600 r/min for

60 Hz systems. Most large nuclear sets rotate at half those speeds, and have a 4-pole

generator rather than the more common 2-pole one.

Energy in the steam after it leaves the boiler is converted into rotational energy as it

passes through the turbine. The turbine normally consists of several stage with each

stages consisting of a stationary blade (or nozzle) and a rotating blade. Stationary blades

convert the potential energy of the steam into kinetic energy into forces, caused by

pressure drop, which results in the rotation of the turbine shaft. The turbine shaft is

connected to a generator, which produces the electrical energy.

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4. Boiler feed water pump

A Boiler feed water pump is a specific type of pump used to pump water into a steam

boiler. The water may be freshly supplied or retuning condensation of the steam

produced by the boiler. These pumps are normally high pressure units that use suction

from a condensate return system and can be of the centrifugal pump type or positive

displacement type.

Figure 8: EXTERNAL VIEW OF BOILER

Construction and operation:

Feed water pumps range in size up to many horsepower and the electric motor is usually

separated from the pump body by some form of mechanical coupling. Large industrial

condensate pumps may also serve as the feed water pump. In either case, to force the

water into the boiler; the pump must generate sufficient pressure to overcome the

steam pressure developed by the boiler. This is usually accomplished through the use of

a centrifugal pump.

Feed water pumps usually run intermittently and are controlled by a float switch or

other similar level-sensing device energizing the pump when it detects a lowered liquid

level in the boiler is substantially increased. Some pumps contain a two-stage switch. As

liquid lowers to the trigger point of the first stage, the pump is activated. I f the liquid

continues to drop (perhaps because the pump has failed, its supply has been cut off or

exhausted, or its discharge is blocked); the second stage will be triggered.

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5. Steam-powered pumps

Steam locomotives and the steam engines used on ships and stationary applications

such as power plants also required feed water pumps. In this situation, though, the

pump was often powered using a small steam engine that ran using the steam produced

by the boiler. A means had to be provided, of course, to put the initial charge of water

into the boiler(before steam power was available to operate the steam-powered feed

water pump).the pump was often a positive displacement pump that had steam valves

and cylinders at one end and feed water cylinders at the other end; no crankshaft was

required.In thermal plants, the primary purpose of surface condenser is to condense the

exhaust steam from a steam turbine to obtain maximum efficiency and also to convert

the turbine exhaust steam into pure water so that it may be reused in the steam

generator or boiler as boiler feed water. By condensing the exhaust steam of a turbine

at a pressure below atmospheric pressure, the steam pressure drop between the inlet

and exhaust of the turbine is increased, which increases the amount heat available for

conversion to mechanical power. Most of the heat liberated due to condensation of the

exhaust steam is carried away by the cooling medium (water or air) used by the surface

condenser.

6. Control valves

Control valves are valves used within industrial plants and elsewhere to control

operating conditions such as temperature, pressure, flow, and liquid Level by fully

partially opening or closing in response to signals received from controllers that

compares a “set point” to a “process variable” whose value is provided by sensors that

monitor changes in such conditions. The opening or closing of control valves is done by

means of electrical, hydraulic or pneumatic systems

7. Deaerator

A Dearator is a device for air removal and used to remove dissolved gases (an alternate

would be the use of water treatment chemicals) from boiler feed water to make it non-

corrosive. A dearator typically includes a vertical domed deaeration section as the

deaeration boiler feed water tank. A Steam generating boiler requires that the

35

circulating steam, condensate, and feed water should be devoid of dissolved gases,

particularly corrosive ones and dissolved or suspended solids. The gases will give rise to

corrosion of the metal. The solids will deposit on the heating surfaces giving rise to

localized heating and tube ruptures due to overheating. Under some conditions it may

give to stress corrosion cracking.

Deaerator level and pressure must be controlled by adjusting control valves- the level by

regulating condensate flow and the pressure by regulating steam flow. If operated

properly, most deaerator vendors will guarantee that oxygen in the deaerated water will

not exceed 7 ppb by weight (0.005 cm3/L)

8. 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 irreversible 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 introduces back into the steam cycle.

In a steam power (usually modeled as a modified Ranking cycle), feed water heaters

allow the feed water to be brought up to the saturation temperature very gradually. This

minimizes the inevitable irreversibility’s associated with heat transfer to the working

fluid (water). A belt conveyor consists of two pulleys, with a continuous loop of material-

the conveyor Belt – that rotates about them. The pulleys are powered, moving the belt

and the material on the belt forward. Conveyor belts are extensively used to transport

industrial and agricultural material, such as grain, coal, ores etc.

9. Pulverizer

A pulverizer is a device for grinding coal for combustion in a furnace in a fossil fuel

power plant.

36

10. Boiler Steam Drum

Steam Drums are a regular feature of water tube boilers. It is reservoir of water/steam

at the top end of the water tubes in the water-tube boiler. They store the steam

generated in the water tubes and act as a phase separator for the steam/water mixture.

The difference in densities between hot and cold water helps in the accumulation of the

“hotter”-water/and saturated –steam into steam drum. Made from high-grade steel

(probably stainless) and its working involves temperatures 390’C and pressure well

above 350psi (2.4MPa). The separated steam is drawn out from the top section of the

drum. Saturated steam is drawn off the top of the drum. The steam will re-enter the

furnace in through a super heater, while the saturated water at the bottom of steam

drum flows down to the mud-drum /feed water drum by down comer tubes accessories

include a safety valve, water level indicator and fuse plug. A steam drum is used in the

company of a mud-drum/feed water drum which is located at a lower level. So that it

acts as a sump for the sludge or sediments which have a tendency to the bottom.

11. Super Heater

A Super heater is a device in a steam engine that heats the steam generated by the

boiler again increasing its thermal energy and decreasing the likelihood that it will

condense inside the engine. Super heaters increase the efficiency of the steam engine,

and were widely adopted. Steam which has been superheated is logically known as

superheated steam; non-superheated steam is called saturated steam or wet steam;

Super heaters were applied to steam locomotives in quantity from the early 20th

century, to most steam vehicles, and so stationary steam engines including power

stations.

12. Economizers

Economizer, or in the UK economizer, are mechanical devices intended to reduce energy

consumption, or to perform another useful function like preheating a fluid. The term

economizer is used for other purposes as well.Boiler, power plant, and heating,

ventilating and air conditioning. In boilers, economizer are heat exchange devices that

heat fluids , usually water, up to but not normally beyond the boiling point of the fluid.

37

Economizers are so named because they can make use of the enthalpy and improving

the boiler’s efficiency. They are a device fitted to a boiler which saves energy by using

the exhaust gases from the boiler to preheat the cold water used the fill it (the feed

water). Modern day boilers, such as those in cold fired power stations, are still fitted

with economizer which is decedents of Green’s original design. In this context they are

turbines before it is pumped to the boilers. A common application of economizer is

steam power plants is to capture the waste hit from boiler stack gases (flue gas) and

transfer thus it to the boiler feed water thus lowering the needed energy input , in turn

reducing the firing rates to accomplish the rated boiler output . Economizer lower stack

temperatures which may cause condensation of acidic combustion gases and serious

equipment corrosion damage if care is not taken in their design and material selection.

13. Air Preheater

Air preheater is a general term to describe any device designed to heat air before

another process (for example, combustion in a boiler). 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 fuel 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.

14. Precipitator

An Electrostatic precipitator (ESP) or electrostatic air cleaner is a particulate device that

removes particles from a flowing gas (such As air) using the force of an induced

electrostatic charge. Electrostatic precipitators are highly efficient filtration devices, and

can easily remove fine particulate matter such as dust and smoke from the air steam.

ESP’s continue to be excellent devices for control of many industrial particulate

emissions, including smoke from electricity-generating utilities (coal and oil fired), salt

cake collection from black liquor boilers in pump mills, and catalyst collection from

fluidized bed catalytic crackers from several hundred thousand ACFM in the largest coal-

fired boiler application.

38

The original parallel plate-Weighted wire design (described above) has evolved as more

efficient ( and robust) discharge electrode designs were developed, today focusing on

rigid discharge electrodes to which many sharpened spikes are attached , maximizing

corona production. Transformer –rectifier systems apply voltages of 50-100 Kilovolts at

relatively high current densities. Modern controls minimize sparking and prevent arcing,

avoiding damage to the components. Automatic rapping systems and hopper evacuation

systems remove the collected particulate matter while on line allowing ESP’s to stay in

operation for years at a time.

15. Fuel gas stack

A Fuel gas stack is a type of chimney, a vertical pipe, channel or similar structure through

which combustion product gases called fuel gases are exhausted to the outside air. Fuel

gases are produced when coal, oil, natural gas, wood or any other large combustion

device. Fuel gas is usually composed of carbon dioxide (CO2) and water vapor as well as

nitrogen and excess oxygen remaining from the intake combustion air. It also contains a

small percentage of pollutants such as particulates matter, carbon mono oxide, nitrogen

oxides and sulfur oxides. The flue gas stacks are often quite tall, up to 400 meters (1300

feet) or more, so as to disperse the exhaust pollutants over a greater aria and thereby

reduce the concentration of the pollutants to the levels required by governmental

environmental policies and regulations.

When the fuel gases exhausted from stoves, ovens, fireplaces or other small sources

within residential abodes, restaurants , hotels or other stacks are referred to as

chimneys.

39

CHAPTER-3

EMD- I

Electrical Maintenance Division I

It is responsible for the maintenance of:

HT/LT MOTORS TURBINE & BOILER SIDEBoiler Side Motors:

For 1, units 1, 2, 3

1. ID Fans 2 in no.

2. FD Fans 2 in no.

3. PA Fans 2 in no.

4. Mill Fans 3 in no.

5. Ball mill fans 3 in no.

6. RC feeders 3 in no.

7. Slag Crushers 5 in no.

8. DM Make up Pump 2 in no.

9. PC Feeders 4 in no.

10. Worm Conveyor 1 in no.

11. Furnikets 4 in no.

For stage units 1, 2, 3

1. I.D Fans 2 in no.

2. F.D Fans 2 in no.

3. P.A Fans 2 in no.

4. Bowl Mills 6 in no.

5. R.C Feeders 6 in no.

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6. Clinker Grinder 2 in no.

7. Scrapper 2 in no.

8. Seal Air Fans 2 in no.

9. Hydrazine & Phosphorous Dozing 2 in no.

Figure 9: EXTERNAL VIEW OF ID, PA & FD FANS

COAL HANDLING PLANT (C.H.P) & NEW COAL HANDLING PLANT (N.C.H.P)The old coal handling plant caters to the need of units 2,3,4,5 and 1 whereas the latter

supplies coal to units 4 and V.O.C.H.P. supplies coal to second and third stages in the

advent coal to usable form to (crushed) form its raw form and send it to bunkers, from

where it is send to furnace.

Figure 10: FLOW CHART OF COAL HANDLING PLANT

41

Major Components

1. Wagon Tippler: - Wagons from the coal yard come to the tippler and are emptied

here. The process is performed by a slip –ring motor of rating: 55 KW, 415V, 1480 RPM.

This motor turns the wagon by 135 degrees and coal falls directly on the conveyor

through vibrators. Tippler has raised lower system which enables is to switch off motor

when required till is wagon back to its original position. It is titled by weight balancing

principle. The motor lowers the hanging balancing weights, which in turn tilts the

conveyor. Estimate of the weight of the conveyor is made through hydraulic weighing

machine.

2. Conveyor: - There are 14 conveyors in the plant. They are numbered so that their

function can be easily demarcated. Conveyors are made of rubber and more with a

speed of 250-300m/min. Motors employed for conveyors has a capacity of 150 HP.

Conveyors have a capacity of carrying coal at the rate of 400 tons per hour. Few

conveyors are double belt, this is done for imp. Conveyors so that if a belt develops any

problem the process is not stalled. The conveyor belt has a switch after every 25-30 m

on both sides so stop the belt in case of emergency. The conveyors are 1m wide, 3 cm

thick and made of chemically treated vulcanized rubber. The max angular elevation of

conveyor is designed such as never to exceed half of the angle of response and comes

out to be around 20 degrees.

3. Zero Speed Switch:-It is safety device for motors, i.e., if belt is not moving and the

motor is on the motor may burn. So to protect this switch checks the speed of the belt

and switches off the motor when speed is zero.

4. Metal Separators: - As the belt takes coal to the crusher, No metal pieces should go

along with coal. To achieve this objective, we use metal separators. When coal is

dropped to the crusher hoots, the separator drops metal pieces ahead of coal. It has a

magnet and a belt and the belt is moving, the pieces are thrown away. The capacity of

this device is around 50 kg. .The CHP is supposed to transfer 600 tons of coal/hr, but

practically only 300-400 tons coal is transfer

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5. Crusher: - Both the plants use TATA crushers powered by BHEL. Motors. The crusher is

of ring type and motor ratings are 400 HP, 606 KV. Crusher is designed to crush the

pieces to 20 mm size i.e. practically considered as the optimum size of transfer via

conveyor.

6. Rotatory Breaker: - OCHP employs mesh type of filters and allows particles of 20mm

size to go directly to RC bunker, larger particles are sent to crushes. This leads to

frequent clogging. NCHP uses a technique that crushes the larger of harder substance

like metal impurities easing the load on the magnetic separators.

3. MILLING SYSTEM

1. RC Bunker: - Raw coal is fed directly to these bunkers. These are 3 in no. per boiler. 4

& ½ tons of coal are fed in 1 hr. the depth of bunkers is 10m.

2. RC Feeder: - It transports pre crust coal from raw coal bunker to mill. The quantity of

raw coal fed in mill can be controlled by speed control of aviator drive controlling

damper and aviator change.

3. Ball Mill: - The ball mill crushes the raw coal to a certain height and then allows it to

fall down. Due to impact of ball on coal and attraction as per the particles move over

each other as well as over the Armor lines, the coal gets crushed. Large particles are

broken by impact and full grinding is done by attraction. The Drying and grinding option

takes place simultaneously inside the mill.

4. Classifier: - It is equipment which serves separation of fine pulverized coal particles

medium from coarse medium. The pulverized coal along with the carrying medium

strikes the impact plate through the lower part. Large particles are then transferred to

the ball mill.

5. Cyclone Separators: - It separates the pulverized coal from carrying medium. The

mixture of pulverized coal vapour caters the cyclone separators.

6. The Tturniket: - It serves to transport pulverized coal from cyclone separators to

pulverized coal bunker or to worm conveyors. There are 4 turnikets per boiler.

43

7. Worm Conveyor: - It is equipment used to distribute the pulverized coal from bunker

of one system to bunker of other system. It can be operated in both directions.

8. Mills Fans: - It is of 3 types:

Six in all and are running condition all the time.

(a) ID Fans: - Located between electrostatic precipitator and chimney.

Type-radical

Speed-1490 rpm

Rating-300 KW

Voltage-6.6 KV

Lubrication-by oil

(b) FD Fans: - Designed to handle secondary air for boiler. 2 in number and provide

ignition of coal.

Type-axial

Speed-990 rpm

Rating-440 KW

Voltage-6.6 KV

(c)Primary Air Fans: - Designed for handling the atmospheric air up to 50 degrees Celsius,

2 in number

And they transfer the powered coal to burners to firing.

Type-Double suction radial

Rating-300 KW

Voltage-6.6 KV

44

Lubrication-by oil

Type of operation-continuous

9. Bowl Mill: - One of the most advanced designs of coal pulverizes presently

manufactured.

Motor Specification

Squirrel cage induction motor

Rating-340 KW

Voltage-6600KV

Curreen-41.7A

Speed-980 rpm

Frequency-50 Hz

No-load current-15-16 A

4. NEW COAL HANDLING PLANT

1. Wagon Tippler:

Motor Specification

(i) H.P 75 HP

(ii) Voltage 415, 3 phase

(iii) Speed 1480 rpm

(iv) Frequency 50 Hz

(v) Current rating 102 A

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2. Coal feed to plant:

Feeder motor specification

(i) Horse power 15 HP

(ii) Voltage 415V, 3 phase

(iii) Speed 1480 rpm

(iv) Frequency 50 Hz

3. Conveyors:-

10A, 10B

11A, 11B

12A, 12B

13A, 13B

14A, 14B

15A, 15B

16A, 16B

17A, 17B

18A, 18B

4. Transfer Point 6

5. Breaker House

6. Rejection House

7. Reclaim House

46

8. Transfer Point 7

9. Crusher House

The coal arrives in wagons via railways and is tippled by the wagon tipplers into the

hoppers. If coal is oversized (>400 mm sq) then it is broken manually so that it passes

the hopper mesh. From the hopper mesh it is taken to the transfer point TP6 by

conveyor 12A ,12B which takes the coal to the breaker house , which renders the coal

size to be 100mm sq. the stones which are not able to pass through the 100mm sq of

hammer are rejected via conveyors 18A,18B to the rejection house . Extra coal is to sent

to the reclaim hopper via conveyor 16. From breaker house coal is taken to the TP7 via

Conveyor 13A, 13B. Conveyor 17A, 17B also supplies coal from reclaim hopper, From

TP7 coal is taken by conveyors 14A, 14B to crusher house whose function is to render

the size of coal to 20mm sq. now the conveyor labors are present whose function is to

recognize and remove any stones moving in the conveyors . In crusher before it enters

the crusher. After being crushed, if any metal is still present it is taken care of by metal

detectors employed in conveyor 10.

5. SWITCH GEAR

It makes or breaks an electrical circuit.

1. Isolation: - A device which breaks an electrical circuit when circuit is switched on to no

load. Isolation is normally used in various ways for purpose of isolating a certain portion

when required for maintenance.

2. Switching Isolation: - It is capable of doing things like interrupting transformer

magnetized current, interrupting line charging current and even perform load transfer

switching. The main application of switching isolation is in connection with transformer

feeders as unit makes it possible to switch out one transformer while other is still on

load.

3. Circuit Breakers: - One which can make or break the circuit on load and even on faults

is referred to as circuit breakers. This equipment is the most important and is heavy duty

47

equipment mainly utilized for protection of various circuits and operations on load.

Normally circuit breakers installed are accompanied by isolators

4. Load Break Switches: - These are those interrupting devices which can make or break

circuits. These are normally on same circuit, which are backed by circuit breakers.

5. Earth Switches: - Devices which are used normally to earth a particular system, to

avoid any accident happening due to induction on account of live adjoining circuits.

These equipments do not handle any appreciable current at all. Apart from this

equipment there are a number of relays etc. which are used in switchgear.

LT Switchgear

It is classified in following ways:-

1. Main Switch: - Main switch is control equipment which controls or disconnects the

main supply. The main switch for 3 phase supply is available for tha range 32A, 63A,

100A, 200Q, 300A at 500V grade.

2. Fuses: - With Avery high generating capacity of the modern power stations extremely

heavy carnets would flow in the fault and the fuse clearing the fault would be required

to withstand extremely heavy stress in process.

It is used for supplying power to auxiliaries with backup fuse protection, rotary switch up

to 25A. With fuses, quick break, quick make and double break switch fuses for 63A and

100A, switch fuses for 200A, 400A, 600A, 800A and 1000A are used.

3. Contractors: - AC Contractors are 3 poles suitable for D.O.L Starting of motors and

protecting the connected motors.

4. Overload Relay: - For overload protection, thermal over relay are best suited for this

purpose. They operate due to the action of heat generated by passage of current

through relay element.

5. Air Circuit Breakers: - It is seen that use of oil in circuit breaker may cause a fire. So in

all circuits breakers at large capacity air at high pressure is used which is maximum at

48

the time of quick tripping of contacts. This reduces the possibility of sparking. The

pressure may vary from 50-60 kg/cm^2 for high and medium capacity circuit breakers.

HT Switch Gear

1. Minimum oil Circuit Breaker: - These use oil as quenching medium. It comprises of

simple dead tank row pursuing projection from it. The moving contracts are carried on

an iron arm lifted by a long insulating tension rod and are closed simultaneously

pneumatic operating mechanism by means of tensions but throw off spring to be

provided at mouth of the control the main current within the controlled device.

Type-HKH 12/1000c

· Rated Voltage-66 KV

· Normal Current-1250A

· Frequency-5Hz

· Breaking Capacity-3.4+KA Symmetrical

· 3.4+KA Asymmetrical

· 360 MVA Symmetrical

· Operating Coils-CC 220 V/DC

§ FC 220V/DC

· Motor Voltage-220 V/DC

2. Air Circuit Breaker: - In this the compressed air pressure around 15 kg per cm^2 is

used for extinction of arc caused by flow of air around the moving circuit . The breaker is

closed by applying pressure at lower opening and opened by applying pressure at upper

opening. When contacts operate, the cold air rushes around the movable contacts and

blown the arc.

49

It has the following advantages over OCB:-

i. Fire hazard due to oil are eliminated.

ii. Operation takes place quickly.

iii. There are less burning contacts since the duration is short and consistent.

iv. Facility for frequent operation since the cooling medium is replaced constantly.

Rated Voltage-6.6 KV

Current-630 A

Auxiliary current-220 V/DC

3. SF6 Circuit Breaker: - This type of circuit breaker is of construction to dead tank bulk

oil to circuit breaker but the principle of current interruption is similar o that of air blast

circuit breaker. It simply employs the arc extinguishing medium namely SF6 the

performance of gas. When it is broken down under an electrical stress, it will quickly

reconstitute itself

· Circuit Breakers-HPA

· Standard-1 EC 56


· Insulation Level-28/75 KV

· Rated Frequency-50 Hz

· Breaking Current-40 KA

· Rated Current-1600 A

· Making Capacity-110 KA

· Rated Short Time Current 1/3s -40 A

· Mass Approximation-185 KG

50

· Auxiliary Voltage

. Closing Coil-220 V/DC

. Opening Coil-220 V/DC

· Motor-220 V/DC

· SF6 Pressure at 20 Degree Celsius-0.25 KG

· SF6 Gas Per pole-0.25 KG

4. Vacuum Circuit Breaker: - It works on the principle that vacuum is used to save the

purpose of insulation and it implies that pr of gas at which breakdown voltage is

independent of pressure. It regards of insulation and strength, vacuum is superior

dielectric medium and is better that all other medium except air and sulphur which are

generally used at high pressure.

· Rated frequency-50 Hz

· Rated making Current-10 Peak KA


· Supply Voltage Closing-220 V/DC

· Rated Current-1250 A

· Supply Voltage Tripping-220 V/DC

· Insulation Level-IMP 75 KVP

· Rated Short Time Current-40 KA (3 SEC), Weight of Breaker-8 KG

51

CHAPTER-3

EMD II

Electrical Maintenance division II

This division is divided as follows

Generator and Auxiliaries Generator Fundamentals

The transformation of mechanical energy into electrical energy is carried out by the

Generator. This Chapter seeks to provide basic understanding about the working

principles and development of Generator.

Figure 11: CROSS-SECTIONAL VIEW OF A GENERATOR

Working Principle

The A.C. Generator or alternator is based upon the principle of electromagnetic

induction and consists generally of a stationary part called stator and a rotating part

called rotor. The stator housed the armature windings. The rotor houses the field

windings. D.C. voltage is applied to the field windings through slip rings. When the rotor

is rotated, the lines of magnetic flux (i.e. magnetic field) cut through the stator windings.

52

This induces an electromagnetic force (EMF) in the stator windings. The magnitude of

this EMF is given by the following expression.

E = 4.44 /O FN volts

0 = Strength of magnetic field in Weber’s.

F = Frequency in cycles per second or Hertz.

N = Number of turns in a coil of stator winding

F = Frequency = P*n/120

Where P = Number of poles

n = revolutions per second of rotor.

From the expression it is clear that for the same frequency, number of poles increases

with decrease in speed and vice versa. Therefore, low speed hydro turbine drives

generators have 14 to 20 poles were as high speed steam turbine driven generators

have generally 2 poles.

Generator component

This deals with the two main components of the Generator viz. Rotor, its winding &

balancing and stator, its frame, core & windings.

Rotor

The electrical rotor is the most difficult part of the generator to design. It revolves in

most modern generators at a speed of 3,000 revolutions per minute. The problem of

guaranteeing the dynamic strength and operating stability of such a rotor is complicated

by the fact that a massive non-uniform shaft subjected to a multiplicity of differential

stresses must operate in oil lubricated sleeve bearings supported by a structure

mounted on foundations all of which possess complex dynamic be behavior peculiar to

them. It is also an electromagnet and to give it the necessary magnetic strength

53

The windings must carry a fairly high current. The passage of the current through the

windings generates heat but the temperature must not be allowed to become so high,

otherwise difficulties will be experienced with insulation. To keep the temperature

down, the cross section of the conductor could not be increased but this would

introduce another problems. In order to make room for the large conductors, body and

this would cause mechanical weakness. The problem is really to get the maximum

amount of copper into the windings without reducing the mechanical strength. With

good design and great care in construction this can be achieved. The rotor is a cast steel

ingot, and it is further forged and machined. Very often a hole is bored through the

centre of the rotor axially from one end of the other for inspection. Slots are then

machined for windings and ventilation.

Rotor winding

Silver bearing copper is used for the winding with mica as the insulation between

conductors. A mechanically strong insulator such as micanite is used for lining the slots.

Later designs of windings for large rotor incorporate combination of hollow conductors

with slots or holes arranged to provide for circulation of the cooling gas through the

actual conductors. When rotating at high speed. Centrifugal force tries to lift the

windings out of the slots and they are contained by wedges. The end rings are secured

to a turned recess in the rotor body, by shrinking or screwing and supported at the other

end by fittings carried by the rotor body. The two ends of windings are connected to slip

rings, usually made of forged steel, and mounted on insulated sleeves.

Rotor balancing

When completed the rotor must be tested for mechanical balance, which means that a

check is made to see if it will run up to normal speed without vibration. To do this it

would have to be uniform about its central axis and it is most unlikely that this will be so

to the degree necessary for perfect balance. Arrangements are therefore made in all

designs to fix adjustable balance weights around the circumference at each end.

54

Stator

Stator frame: The stator is the heaviest load to be transported. The major part of this

load is the stator core. This comprises an inner frame and outer frame. The outer frame

is a rigid fabricated structure of welded steel plates, within this shell is a fixed cage of

girder built circular and axial ribs. The ribs divide the yoke in the compartments through

which hydrogen flows into radial ducts in the stator core and circulate through the gas

coolers housed in the frame. The inner cage is usually fixed in to the yoke by an

arrangement of springs to dampen the double frequency vibrations inherent in 2 pole

generators. The end shields of hydrogen cooled generators must be strong enough to

carry shaft seals. In large generators the frame is constructed as two separate parts. The

fabricated inner cage is inserted in the outer frame after the stator core has been

constructed and the winding completed. Stator core: The stator core is built up from a

large number of 'punching" or sections of thin steel plates. The use of cold rolled grain-

oriented steel can contribute to reduction in the weight of stator core for two main

reasons:

a) There is an increase in core stacking factor with improvement in lamination cold

Rolling and in cold buildings techniques.

b) The advantage can be taken of the high magnetic permeance of grain-oriented steels

of work the stator core at comparatively high magnetic saturation without fear or

excessive iron loss of two heavy a demand for excitation ampere turns from the

generator rotor.

Stator Windings

Each stator conductor must be capable of carrying the rated current without

overheating. The insulation must be sufficient to prevent leakage currents flowing

between the phases to earth. Windings for the stator are made up from copper strips

wound with insulated tape which is impregnated with varnish, dried under vacuum and

hot pressed to form a solid insulation bar. These bars are then place in the stator slots

and held in with wedges to form the complete winding which is connected together at

each end of the core forming the end turns. These end turns are rigidly braced and

55

packed with blocks of insulation material to withstand the heavy forces which might

result from a short circuit or other fault conditions. The generator terminals are usually

arranged below the stator. On recent generators (210 MW) the windings are made up

from copper tubes instead of strips through which water is circulated for cooling

purposes. The water is fed to the windings through plastic tubes.

Generator Cooling System

The 200/210 MW Generator is provided with an efficient cooling system to avoid

excessive heating and consequent wear and tear of its main components during

operation. This Chapter deals with the rotor-hydrogen cooling system and stator water

cooling system along with the shaft sealing and bearing cooling systems.

Rotor Cooling System

The rotor is cooled by means of gap pick-up cooling, wherein the hydrogen gas in the air

gap is sucked through the scoops on the rotor wedges and is directed to flow along the

ventilating canals milled on the sides of the rotor coil, to the bottom of the slot where it

takes a turn and comes out on the similar canal milled on the other side of the rotor coil

to the hot zone of the rotor. Due to the rotation of the rotor, a positive suction as well as

discharge is created due to which a certain quantity of gas flows and cools the rotor. This

method of cooling gives uniform distribution of temperature. Also, this method has an

inherent advantage of eliminating the deformation of copper due to varying

temperatures.

Hydrogen Cooling System

Hydrogen is used as a cooling medium in large capacity generator in view of its high heat

carrying capacity and low density. But in view of it’s forming an explosive mixture with

oxygen, proper arrangement for filling, purging and maintaining its purity inside the

generator have to be made. Also, in order to prevent escape of hydrogen from the

generator casing, shaft sealing system is used to provide oil sealing.

The hydrogen cooling system mainly comprises of a gas control stand, a drier, an liquid

level indicator, hydrogen control panel, gas purity measuring and indicating instruments,

56

The system is capable of performing the following functions:

I. Filling in and purging of hydrogen safely without bringing in contact with air.

II. Maintaining the gas pressure inside the machine at the desired value at all the

times.

III. Provide indication to the operator about the condition of the gas inside the

machine i.e. its pressure, temperature and purity.

IV. Continuous circulation of gas inside the machine through a drier in order to

remove any water vapor that may be present in it.

V. Indication of liquid level in the generator and alarm in case of high level.

Stator Cooling System

The stator winding is cooled by distillate.

Turbo generators require water cooling arrangement over and above the usual

hydrogen cooling arrangement. The stator winding is cooled in this system by circulating

demineralised water (DM water) through hollow conductors. The cooling water used for

cooling stator winding calls for the use of very high quality of cooling water. For this

purpose DM water of proper specific resistance is selected. Generator is to be loaded

within a very short period if the specific resistance of the cooling DM water goes beyond

certain preset values. The system is designed to maintain a constant rate of cooling

water flow to the stator winding at a nominal inlet water temperature of 400C.

Rating of 95 MW Generator-

Manufacture by Bharat heavy electrical Limited (BHEL)

Capacity - 117500 KVA

Voltage - 10500V

Speed - 3000 rpm

Hydrogen - 2.5 Kg/cm2

Power factor - 0.85 (lagging)

Stator current - 6475 A

57

Frequency - 50 Hz

Stator winding connection - 3 phase

Rating of 210 MW Generator-

Manufacture by Bharat heavy electrical Limited (BHEL)

Capacity - 247000 KVA

Voltage (stator) - 15750 V

Current (stator) - 9050 A

Voltage (rotor) - 310 V

Current (rotor) - 2600 V

Speed - 3000 rpm

Power factor - 0.85

Frequency - 50 Hz

Hydrogen - 3.5 Kg/cm2

Stator winding connection - 3 phase star connection

Insulation class - B

TransformerA transformer is a device that transfers electrical energy from one circuit to another by

magnetic coupling without requiring relative motion between its parts. It usually

comprises two or more coupled windings, and in most cases, a core to concentrate

magnetic flux. An alternating voltage applied to one winding creates a time-varying

magnetic flux in the core, which includes a voltage in the other windings. Varying the

relative number of turns between primary and secondary windings determines the ratio

of the input and output voltages, thus transforming the voltage by stepping it up or

down between circuits. By transforming electrical power to a high-voltage, _low-current

form and back again, the transformer greatly reduces energy losses and so enables the

economic transmission of power over long distances. It has thus shape the electricity

supply industry, permitting generation to be located remotely from point of demand. All

58

but a fraction of the world’s electrical power has passed through a series of transformer

by the time it reaches the consumer.

Rating of transformer

Manufactured by Bharat Heavy Electrical Limited

No load voltage (HV) - 229 KV

No load Voltage (LV) -10.5 KV

Line current (HV) -315.2 A

Line current (LV) - 873.2 A

Temp rise - 45 Celsius

Oil quantity - 40180 lit

Weight of oil - 34985 Kg

Total weight - 147725 Kg

Core & winding - 84325 Kg

Phase -3

Frequency - 50 Hz

59

C HAPTER-4

CONTROL AND INSTRUMENTATION

This division is basically brain of the power plant and this division is responsible for:

1. Fr controlling the entire process of boiler, turbine n generator.

2. Is responsible for protection of boiler turbine & generator & associated auxiliaries.

3. It is responsible for display of all the parameters to the operator for taking the manual action in case of emergency.

4. Responsible for logging of sequence of events taking place in the control room

Figure 12: CONTROL UNIT

60

This department is the brain of the plant because from the relays to transmitters

followed by the electronic computation chipsets and recorders and lastly the controlling

circuitry, all fall under this.

This division also calibrates various instruments and takes care of any faults occurring in

any of the auxiliaries in the plant provided for all the equipments. Tripping can be

considered as the series of instructions connected through OR GATE. When the main

equipments of this laboratories are relay and circuit breakers.

GENESIS OF THE PROJECT:

There are very transient conditions during the light up of the boiler. At this point, the

level in the drum fluctuates heavily & frequently. So, if the drum level works on properly

on auto loop, then it will be huge relief to operator and it may even save the unit from

tripping on drum level protection. That is why this project is chosen.

OBJECTIVE:

The objective of the boiler drum level control strategy is to maintain the water/steam

interface at its optimum level to provide a continuous mass/heat balance by replacing

every pound of steam leaving the boiler with a pound of feed water to replace it. As

mentioned above if the level is above +175mm then the turbine may get damaged or if

the level is below -175mm then the boiler happens to starvation. The objective of the

entire project is to design the controlling element for the control of valve of drum which

can be designed manually and automatically both. The controlling element will control

the opening and closing of valve of drum according to error signal generated by I-06R

mini card. To serve this purpose the following steps are to be taken

The following are the main objectives of the project:

1) Understanding the input measurement techniques.

2) Understanding the control logic and hence designing it.

3) Understanding and simulating the controlling element i.e. valve actuator.

61

MAIN OUTLINE:

The level in the drum has to be controlled effectively.

If level in the drum is very low say below -175 mmwcl, then the starvation of the water

tubes will take place & hence huge financial loss to the plant will take place.

If the level in the drum is very high say +175 mmwcl then, water particle may enter in

the turbine & turbine blades may get damaged. So, again a huge financial loss to the

plant may take place that is why the drum level is of very high importance.

62

The entire functioning of any auto loop may be primarily being divided in to four parts.

1) Measurement of Input: This is the first step towards designing the auto controller. In

this project, we will study the various measurement techniques of the drum level.

Primarily we will focus on the two techniques as-

i) Drum level measurement technique by differential pressure

measurement: In this variable head is compared with constant head and

thus giving the variable electrical signal in terms of the 4 to 20 ma. This

DP signal is corrected for the density by measuring the drum pressure

and temperature of the saturated steam.

ii) Hydra step measurement: This method is based on the principle of the

resistivity difference of the steam & water. This method gives the

discrete signal hence cannot be used for the auto controlling of the

drum level

2) Designing the control logic: The Corrected drum level signal is compared with the

desired set point & hence error signal is generated. Based on the error signal, the

raise or lower command goes to the controlling element. Here in the auto controlling

of the drum level, we may go for two types of logic-

i) Single element control logic: In this only drum level signal is compared

with the desired set point & thus on the basis of the error signal, raise &

lower command is sent to the controlling element. Here in this project

we are focusing on the single element controller.

ii) Three element control logic: In this, instead of considering only the

drum level we will focus on the two other parameters which are Total

Feed water flow and total steam flow. Designing the three element

controller may be the extension of this project.

3) Designing the controlling element: There are three control elements as follows:

63

a) Electrical/Linear Actuator: A linear actuator is an actuator that creates motion in

a straight line, as contrasted with circular motion of a conventional electric

motor.

Linear actuators are used in machine tools and industrial machinery, in

computer peripherals such as disk drives and printers, in valves and dampers,

and in many other places where linear motion is required. Hydraulic or

pneumatic cylinders inherently produce linear motion; many other mechanisms

are used to provide a linear motion from a rotating motor.

b) Pneumatic Actuator: A pneumatic actuator converts energy (typically in the form

of compressed air) into mechanical motion. The motion can be rotary or linear,

depending on the type of actuator. Some types of pneumatic actuators include:

Tie rod cylinders

Rotary actuators

Grippers

Rod Less actuators with magnetic linkage or rotary cylinder

Rod Less actuators with mechanical linkage

Pneumatic artificial muscles

Vacuum generators

c) Hydraulic Actuator: A Hydraulic cylinder is a mechanical actuator that is used to

give a unidirectional force through a unidirectional stroke. It has many

applications, notably in engineering vehicles. Hydraulic cylinders get their power

from pressurized hydraulic fluid, which is typically oil. The hydraulic cylinder

consists of a cylinder barrel, in which a piston connected to a piston rod moves

back and forth. The barrel is closed on each end by the cylinder bottom (also

called the cap end) and by the cylinder head where the piston rod comes out of

the cylinder. The piston has sliding rings and seals. The piston divides the inside

of the cylinder in two chambers, the bottom chamber (cap end) and the piston

rod side chamber (rod end). The hydraulic pressure acts on the piston to do

linear work and motion.

64

BLOCK DIAGRAM

DESCRIPTION OF BLOCK DIAGRAM

There are two main circuits used in this project. The command for valve actuator can be

given in manual and auto mode both. The circuits for manual & auto command are

different. The circuit for auto command is in parallel with the circuit for manual

command. The block diagram for the circuit for is shown below.

In the circuit of manual mode, the main supply is of 230V AC. The supply is given to the

AC to DC converter. The converter converts 230V AC to 24V DC. This DC supply is given

to the dextile, the dextile and limit switches are connected in parallel. The output of

dextile is given to the DC relays. The DC relays provide 24V as input and 230V as output.

The output of DC relay is given to the contactor which accepts 230V as input and output

both & the output of the contactor is fed to the single phase AC motor.

65

If boundary limits are reached as full open or full close then on giving any further

command will not be executed by the motor.

The energized relay will rotate the motor either in clockwise or in anticlockwise direction

depending upon the energisation. The opening and closing of the valve will depend on

the direction of motor. The motor will control the opening and closing of valve which

will control the level of water in drum. It is necessary to keep track of one thing that at

one time only one relay should get energized either forward relay or backward relay,

hence forward or reverse connectors are used to avoid the simultaneous energization of

both forward and backward relays. The forward relay helps the motor to rotate in

clockwise direction and the backward relay makes the motor to rotate in anticlockwise

direction.

In the circuit of auto mode the I 06 R mini card is used. The I-06 R card is used to make

the

summator subtractor circuit. The card is uses a low current offset differential amplifier,

with feedback arranged to produce the required computing function. The amplifier

which is used to make this 06 r card is used in non-inverting mode. For current input

signals, conditioning resistors are fitted across the input terminals. These resistors are

placed in specific order. There are two inputs of the I-06 R card as one is reference level

and other is variable supply. The 06 R mini card gives error signal as its output.

According to this error signal the trigger circuit will energize the corresponding relay.

The output of I-06 computing Mini Card which is an error signal will be send to the

trigger circuit. The trigger circuit will generate the pulses of +20 V and -20 V which is

send to the forward or backward relays.

The output of the trigger circuit will energize one of the relay either forward or reverse

relay. The 555 timer IC is used in the trigger circuit. The output of the trigger circuit is

fed to the 12V dc relays. Then these 12V relays will energize the 24 V DC relays.

66

CIRCUIT DIAGRAM

There are two main circuits used in this project. The command for valve actuator can be

given in manual and auto mode both. The circuits for manual & auto command are

different. The circuit for auto command is in parallel with the circuit for manual

command.

CIRCUIT DESCRIPTION OF AUTO MODE

CIRCUIT DIAGRAM FOR SET POINT:

The 7805 IC is used for the set input which is given to the I-06R mini card. 20V is given as

input to the 7805 voltage regulator IC. The output of the 7805 is 5V which is constant

67

and we are using 5V as set point of the I 06 R mini card. The 20v is fed to the pin 1 of IC

and output is being taken from pin 3 of IC

CIRCUIT DAIGRAM FOR VARIABLE INPUT

The output voltage is stabilized and is regulated in the region from 0V until + 15V dc,

with biggest provided current 1 A. The regulation becomes with the R2. The Q1 of is

classic power transistor and it needs it is placed in heat sink, one and heating when it

works continuously in the region of biggest current. The type of transformer is standard

in the market. The variable resistor or potentiometer gives as variable output from 0 to

+15V which are given as one of the input of I-06 R mini card.

I-06R MINI CARD CIRCUIT DIAGRAM

68

The I-06 R card is used to make the summator subtractor circuit. The card is uses a low

current offset differential amplifier, with feedback arranged to produce the required

computing function. The amplifier which is used to make this 06 r card is used in non-

inverting mode. For current input signals, conditioning resistors are fitted across the

input terminals. These resistors are placed in specific order. There are two inputs of the

I-06 R card as one is reference level and other is the output of potentiometer which is

variable in nature.

There are three input pins of this card as 1, 2. And 3 of the I 06 R mini card .There are

two inputs applied to the 06 R mini card to generate the error signal. One is reference or

set point which is applied to the pin 1 of this card and second is variable input which is

applied to the pin 2 of the card+20V is applied to the pin 8 of card and -20V is applied to

the pin 10 of the card. The +20V and -20V are applied to the card to drive the card. The

output is being taken from the pin 4 of the card with reference to the ground which is at

pin 09 of card. When less than the total available inputs are in use, the unused inputs

should be connected to the common line hence pin 3 is connected to the common line

or 0V.

TRIGGER CIRCUIT

69

The output of I-06 computing Mini Card which is an error signal will be send to the

trigger circuit. The trigger circuit will generate the pulses of +20 V and -20 V which is

send to the forward or backward relays.

The two comparator inputs (pin 2 & 6) are tied together and biased at 1/2 Vcc through a

voltage divider R1 and R2.Since the threshold comparator wil trip at 2/3 Vcc and the

trigger comparator will trip at 1/3Vcc,the bias provided by the resistors R1 & R2 are

centered within the comparators trip limits.

By modifying the input time constant on the circuit,reducing the value of input capacitor

(C1) to 0.001 uF so that the input pulse get differentiated,the arrangement can also be

used either as a bistable device or to invert pulse wave forms.In the later case ,the fast

time combination of C1 with R1 & R2 causes only the edges of the input pulse or

rectangular waveform to be passed. These pulses set and reset the flip-flop and a high

level inverted output is the result.

ELECTRICAL ACTUATOR CIRCUIT

The output of the trigger circuit will energize one of the relay either forward or reverse

relay. The energized relay will rotate the motor either in clockwise or anticlockwise

direction depends on the type of energized relay. The opening and closing of valve will

depend on the direction of motor. The motor will control the opening and closing of

valve which will control the level of water in drum. It is necessary to keep track of one

thing that at one time only one relay should get energized either forward relay or

70

backward relay, hence forward or reverse connectors are used to avoid the

simultaneous energization of both forward and backward relays.

DEXTILE, LIMIT SWITCH and RELAY PIN DESCRIPTION

The port P12 and P11 gets supply of negative and positive 24 volts respectively. The

positive terminal of limit switch is connected to P4 and P6 terminal of the dextile,

negative terminal of limit switch is connected to fourth port of relay. The port 12 of the

dextile is connected to the eight port of the relay. P1 and P3 of dextile is connected to

the fourth port of forward and backward relay respectively. The connection on port P1

helps to glows yellow colour LED and green colour LED on P3. The port 3 of the relays

gets a supply of 230 volts. NC of contactor is connected to the second port of relays. The

A1 port of both parts of the contactor is on neutral. A1 port of the first part of contactor

is connected to NC of second part of contactor and vice versa. L1 port of both parts of

contactor gets a supply of 230 volts. The first part of the contactor is directly connected

to the motor and the second part of the contactor is connected to the motor in series

with a capacitor to provide an anticlockwise movement.

CONCLUSION:

. Practically there are many parameters to be controlled to maintain the level of water in

drum according to the requirement but we have considered only one parameter of flow

of water in our project. The content of steam which is going in turbine depends on the

level of water in drum hence water level should be in control. To fulfill this purpose we

had designed a controlling element which is receiving command by the trigger circuit.

The trigger circuit is correcting the error signal generated by I-06R mini card and

providing appropriate command to the motor.

EXTENSIONS

1) Triggering circuit may be the economical replace of the 74 R card.

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2) If drum level is put on auto loop during the lighted up condition of the

boiler, there will be huge saving of monetary losses.

3) Timely synchronisation of the unit is possible and hence can better serve

the society.

COMPONENTS DESCRIPTION

LIMIT SWITCH

In electrical engineering a limit switch is a switch operated by the motion of a machine

part or presence of an object. They are used for control of a machine, as

safety interlocks, or to count objects passing a point.

Limit switch is one type Of " Contact Sensor”, In that there is Normally Open Contact &

Normally Close Contact, In limit switch there is Plunger it is Directly Connected to NO &

NC Contact if we press the plunger NO contact become NC & NC contact become NO,

Working Principle same as Contactor (DOL starter) main difference is in contactor There

is Coil to attract the Plunger But In Limit Switch Plunger is Operated Mechanically. Limit

Switches is used mainly for Safety Purpose & to take Feed back for PLC in Automation

industries.

Many limit switches have three terminals. One is the normally closed contact, another

the normally open contact and the third is the common that switches between these

two as the mechanism is moved.

The limit switch is mounted in such a way when the mechanism driven by motor reaches

one of the limit positions, it will engage the limit switch at that position. This will cause

NC contacts of that switch to open and its NO to close.

RELAY

A relay is an electrically operated switch. Many relays use an electromagnet to operate a

switching mechanism mechanically, but other operating principles are also used. Relays

are used where it is necessary to control a circuit by a low-power signal (with complete

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electrical isolation between control and controlled circuits), or where several circuits

must be controlled by one signal. The first relays were used in long distance telegraph

circuits, repeating the signal coming in from one circuit and re-transmitting it to another.

Relays were used extensively in telephone exchanges and early computers to perform

logical operations.

A type of relay that can handle the high power required to directly control an electric

motor or other loads is called a contactor. Solid-state relays control power circuits with

no moving parts, instead using a semiconductor device to perform switching. Relays

with calibrated operating characteristics and sometimes multiple operating coils are

used to protect electrical circuits from overload or faults; in modern electric power

systems these functions are performed by digital instruments still called "protective

relays".

It is a protective device. It can detect wrong condition in electrical circuits by constantly

measuring the electrical quantities flowing under normal and faulty conditions. Some of

the electrical quantities are voltage, current, phase angle and velocity.

CONTACTOR RELAY

A contactor is a very heavy-duty relay used for switching electric motors and lighting loads,

although contactors are not generally called relays. Continuous current ratings for common

contactors range from 10 amps to several hundred amps. High-current contacts are made with

alloys containing silver. The unavoidable arcing causes the contacts to oxidize; however, silver

oxide is still a good conductor. Such devices are often used for motor starters. A motor starter is

a contactor with overload protection devices attached. The overload sensing devices are a form

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of heat operated relay where a coil heats a bi-metal strip, or where a solder pot melts, releasing

a spring to operate auxiliary contacts. These auxiliary contacts are in series with the coil. If the

overload senses excess current in the load, the coil is de-energized. Contactor relays can be

extremely loud to operate, making them unfit for use where noise is a chief concern.

A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core,

an iron yoke which provides a low reluctance path for magnetic flux, a movable

iron armature, and one or more sets of contacts (there are two in the relay pictured).

The armature is hinged to the yoke and mechanically linked to one or more sets of

moving contacts. It is held in place by a spring so that when the relay is de-energized

there is an air gap in the magnetic circuit. In this condition, one of the two sets of

contacts in the relay pictured is closed, and the other set is open. Other relays may have

more or fewer sets of contacts depending on their function. The relay in the picture also

has a wire connecting the armature to the yoke. This ensures continuity of the circuit

between the moving contacts on the armature, and the circuit track on the printed

circuit board (PCB) via the yoke, which is soldered to the PCB

When an electric current is passed through the coil it generates a magnetic field that

activates the armature and the consequent movement of the movable contact either

makes or breaks (depending upon construction) a connection with a fixed contact. If the

set of contacts was closed when the relay was de-energized, then the movement opens

the contacts and breaks the connection, and vice versa if the contacts were open. When

the current to the coil is switched off, the armature is returned by a force, approximately

half as strong as the magnetic force, to its relaxed position. Usually this force is provided

by a spring, but gravity is also used commonly in industrial motor starters.

When the coil is energized with direct current, a diode is often placed across the coil to

dissipate the energy from the collapsing magnetic field at deactivation, which would

otherwise generate a voltage spike dangerous to semiconductor circuit components.

Some automotive relays include a diode inside the relay case. Alternatively, a contact

protection network consisting of a capacitor and resistor in series (snubber circuit) may

absorb the surge. If the coil is designed to be energized with alternating current (AC), a

small copper "shading ring" can be crimped to the end of the solenoid, creating a small

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out-of-phase current which increases the minimum pull on the armature during the AC

cycle.

A solid-state relay uses a thyristor or other solid-state switching device, activated by the

control signal, to switch the controlled load, instead of a solenoid.

An optocoupler (a light-emitting diode (LED) coupled with a photo transistor) can be

used to isolate control and controlled circuits.

OPERATING PRINCIPLE

Unlike general-purpose relays, contactors are designed to be directly connected to high-

current load devices. Relays tend to be of lower capacity and are usually designed for

both normally closed and normally open applications. Devices switching more than 15

amperes or in circuits rated more than a few kilowatts are usually called contactors.

Apart from optional auxiliary low current contacts, contactors are almost exclusively

fitted with normally open contacts. Unlike relays, contactors are designed with features

to control and suppress the arc produced when interrupting heavy motor currents.

When current passes through the electromagnet, a magnetic field is produced, which

attracts the moving core of the contactor? The electromagnet coil draws more current

initially, until its inductance increases when the metal core enters the coil. The moving

contact is propelled by the moving core; the force developed by the electromagnet

holds the moving and fixed contacts together. When the contactor coil is de-energized,

gravity or a spring returns the electromagnet core to its initial position and opens the

contacts.

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For contactors energized with alternating current, a small part of the core is surrounded

with a shading coil, which slightly delays the magnetic flux in the core. The effect is to

average out the alternating pull of the magnetic field and so prevent the core from

buzzing at twice line frequency.

7805 VOLTAGE REGULATOR IC

The 7805 is a self-contained fixed linear voltage regulator integrated circuit.. The voltage

regulator ic family is commonly used in electronic circuits requiring a regulated power supply

due to their ease-of-use and low cost. The 7805 line is positive voltage regulators: they produce

a voltage that is positive relative to a common ground.

7805 ICs have three terminals and are commonly found in the TO220 form factor,

although smaller surface-mount and larger TO3 packages are available. These devices

support an input voltage anywhere from a couple of volts over the intended output

voltage, up to a maximum of 35 to 40 volts depending on the make, and typically

provide 1 or 1.5 amperes of current (though smaller or larger packages may have a

lower or higher current rating).

7805 series ICs do not require additional components to provide a constant, regulated

source of power, making them easy to use, as well as economical and efficient uses of

space. Other voltage regulators may require additional components to set the output

voltage level, or to assist in the regulation process. Some other designs (such as

a switched-mode power supply) may need substantial engineering expertise to

implement.

7805 series ICs have built-in protection against a circuit drawing too much power. They have

protection against overheating and short-circuits, making them quite robust in most

applications. In some cases, the current-limiting features of the 7805 devices can provide

protection not only for the 7805 itself, but also for other parts of the circuit.

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7805 ICs are easy to use and handle but these cannot give an altering voltage required

so LM317 series of ICs are available to obtain a voltage output from 1.25 volts to 37

volts.

2N3055 TRANSISTOR

The 2N3055 is a silicon NPN power transistor intended for general purpose applications.

The horizontal output transformer from a CRT type TV can be driven using just two resistors and

a 2N3055 in fly back mode, transforming a low voltage, such as 12 volts, into several kilovolts.

The output is very low current, so there is a minimal chance of dangerous electric shock.

However, the design is limited by the 2N3055's ability to handle this sort of circuit, and will

overheat and quickly fail from the inductive voltage feedback spikes from the transformer.

Hobbyists would, after gaining an understanding of high voltage, then move on to higher power

circuits and transformers. This transistor must be counted among the hobbyists as the most

used power transistor, after being used in audio power amplifier with powers ranging from 10W

to 400W.

555 TIMER IC

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and

oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-

flop element. Derivatives provide up to four timing circuits in one package.

The IC was designed in 1971 by Hans R. Camenzind under contract to Signetics, which

was later acquired by Philips.Depending on the manufacturer, the standard 555 package

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includes 25 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin

mini dual-in-line package (DIP-8).[2] Variants available include the 556 (a 14-pin DIP

combining two 555s on one chip), and the two 558 & 559s (both a 16-pin DIP combining

four slightly modified 555s with DIS & THR connected internally, and TR is falling edge

sensitive instead of level sensitive). There is no 557.

The NE555 parts were commercial temperature range, 0 °C to +70 °C, and the SE555

part number designated the military temperature range, −55 °C to +125 °C. These were

available in both high-reliability metal can (T package) and inexpensive epoxy plastic (V

package) packages. Thus the full part numbers were NE555V, NE555T, SE555V, and

SE555T. It has been hypothesized that the 555 got its name from the three 5 kΩ resistors

used within, but Hans Camenzind has stated that the number was arbitrary.

Pin Diagram

The connection of the pins for a DIP package is as follows:

Pin Name Purpose

1 GND Ground, low level (0 V)

2 TRIG OUT rises, and interval starts, when this input falls below 1/2 of CTRL voltage.

3 OUT This output is driven to approximately 1.7V below + V CC or GND.

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4 RESET

A timing interval may be reset by driving this input to GND, but the timing

does not begin again until RESET rises above approximately 0.7 volts. Overrides TRIG

which overrides THR.

5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).

6 THR The interval ends when the voltage at THR is greater than at CTRL.

7 DIS Open collector output; may discharge a capacitor between intervals. In phase

with output.

8 VCC Positive supply voltage is usually between 3 and 15 V.

Note-PIN 5 is also called the CONTROL VOLTAGE pin by applying a voltage to the

CONTROL VOLTAGE input you can alter the timing characteristics of the device. In most

applications, the CONTROL VOLTAGE input is not used. It is usual to connect a 10 nF

capacitor between pin 5 and 0 V to prevent interference. The CONTROL VOLTAGE input

can be used to build an astable with a frequency modulated output.

SPECIFICATION

These specifications apply to the NE555. Other 555 timers can have

different specifications depending on the grade (military, medical, etc.).

Supply voltage (VCC) 4.5 to 15 V

Supply current (VCC = +5 V) 3 to 6 mA

Supply current (VCC = +15 V) 10 to 15 mA

Output current (maximum) 200 mA

Maximum Power dissipation 600 mW

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Power consumption (minimum operating) 30 mW@5V, 225 mW@15V

Operating temperature 0 to 70 °C

SINGLE PHASE AC MOTOR

An AC motor is an electric motor driven by an alternating current.

It commonly consists of two basic parts, an outside stationary stator having coils

supplied with alternating current to produce a rotating magnetic field, and an inside

rotor attached to the output shaft that is given a torque by the rotating field.

There are two main types of AC motors, depending on the type of rotor used. The first

type is the induction motor, which runs slightly slower than the supply frequency. The

magnetic field on the rotor of this motor is created by an induced current. The second

type is the synchronous motor, which does not rely on induction and as a result, can

rotate exactly at the supply frequency or a sub-multiple of the supply frequency. The

magnetic field on the rotor is either generated by current delivered through slip rings or

by a permanent magnet. Other types of motors include eddy current motors, and also

AC/DC mechanically commutated machines in which speed is dependent on voltage and

winding connection

Induction motor has a rotating (relative to the rotor) magnetic field on the rotor. In a

squirrel cage motor, this field is created because the motion of the stator field relative to

the shorted rotor cage induces currents in the rotor. These currents generate the rotor

field, which interacts with the stator field to create torque. A wound-rotor induction

machine has rotor windings similar to a synchronous machine, in which currents are

induced by the rotating stator field. Induction motors always rotate in some narrow

speed range that is less than synchronous speed. This speed difference, which is

necessary to generate the rotor field, is called the "slip." Low slip machines, which turn

at very near synchronous speed, are more efficient than high slip machines, but have

lower starting torque. Induction machines can produce some torque at zero speed, so

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they are capable of starting themselves if the load torque is low enough at zero speed.

The torque-speed characteristic of induction machines at rated speed has a negative

slope (as speed decreases, torque increases). As a result, induction machines do not

require controls to operate - the feedback mechanism is built into the machine.

The winding resistance a wound-rotor induction machine can be varied by connecting

resistors to the rotor windings via the slip rings. This allows the torque-speed

characteristics of the wound-rotor machine to be varied as needed (e.g., high resistance

and high slip for high starting torque and then low resistance and low slip for high

efficiency at rated speed).

The absence of a rotor winding makes squirrel cage induction machines significantly

cheaper to manufacture than synchronous machines (or wound-rotor induction

machines). Squirrel cage machines are extremely rugged because of the lack of a wound

rotor (the cage is usually cast right into the rotor laminations), and the lack of slip rings

makes them more suitable for explosive environments because there is no arcing

mechanism. The circulating currents in an induction machine rotor lead to resistive

losses that make induction machines less efficient that synchronous motor.

MAIN CHARACTERSTICS OF INDUCTION MOTOR:

Wound-rotor or squirrel cage to generate the rotor magnetic field.

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Rotor magnetic field rotates with respect to the rotor.

Always turn at less than synchronous speed.

Do not require control.

Much cheaper to produce (true for squirrel cage machines).

Self-starting.

Less efficient than synchronous machines.

More suitable for explosive environments.

No maintenance (for squirrel cage machines).

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NTPC BADARPUR PROJECT REPORT

Engineering

Transcript of NTPC BADARPUR PROJECT REPORT