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 Contents
Table of Contents...........................................................................................................................4
CHAPTER-1..............................................................................................6
COMPANY PROFILE........................................................................................................................6
VISION AND MISSION.................................................................................................................6
Core Values – BE COMMITTED...................................................................................................6
POWER GENERATION IN INDIA..................................................................................................7
EVOLUTION................................................................................................................................9
STRATEGIES..............................................................................................................................11
NTPC HEADQUARTERS.............................................................................................................11
NTPC Limited is divided in 8 Headquarters..............................................................................11
NTPC PLANTS............................................................................................................................11
FUTURE GOALS.........................................................................................................................14
POWER BURDEN.......................................................................................................................14
ENVIRONMENT POLICY & ENVIRONMENT MANAGEMENT SYSTEM........................................14
NATIONAL ENVIRONMENT POLICY ..........................................................................................15
NTPC ENVIRONMENT POLICY ..................................................................................................15
ENVIRONMET MANAGEMENT, OCCUPATIONAL HEALTH and SAFETY SYSTEMS .....................15
POLLUTION CONTROL SYSTEMS...............................................................................................16
UP GRADATION & RETROFITTING of POLLUTION CONTROL SYSTEMS.....................................20
OVERALL POWER GENERATION................................................................................................21
CHAPTER-2...................................................................................................................................22
ABOUT BADARPUR THERMAL POWER STATION..........................................................................22
BADARPUR THERMAL POWER STATION...................................................................................22
FROM COAL TO ELECTRICITY PROCESS....................................................................................23
MAIN GENERATOR ..................................................................................................................28
MAIN TURBINE DATA...............................................................................................................29

4

OPERATION..............................................................................................................................29
CHAPTER-3.........................................................................................................40
EMD- I.........................................................................................................40
HT/LT MOTORS TURBINE & BOILER SIDE..................................................................................40
COAL HANDLING PLANT (C.H.P) & NEW COAL HANDLING PLANT (N.C.H.P).............................42
CHAPTER-3..............................................................................................52
EMD II...........................................................................................................................................52
Generator and Auxiliaries ........................................................................................................52
Transformer.............................................................................................................................59
CHAPTER-4....................................................................................60
CONTROL AND INSTRUMENTATION.............................................................................................60
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 ......................................................................................................................................

5

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

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 MISSION
Vision
“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
C

Environmentally & Economically Sustainable
Customer Focus

O
M

Organizational & Professional Pride
Mutual Respect & Trust

M
I

Motivating Self & others
Innovation & Speed
6

T

Total Quality for Excellence

T
E

Transparent & Respected Organization
Enterprising

D

Devoted

Figure 1: NTPC OPERATION GRAPH

POWER GENERATION IN INDIA
NTPC’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

8

Development (USAID). Cenpeep is efficiency oriented, eco-friendly and eco-nurturing
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
1975
1975

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.

1997
1997

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

2004
2004

NTPC became a listed company with majority Government
ownership of 89.5%. NTPC becomes third largest by market
capitalisation of listed companies.

2005
2005

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
2008
2008

generation company in India. Forbes Global 2000 for 2008 ranked
it 411th the world.

2009
2009

National Thermal Power Corporation is the largest power
generation company in India. Forbes Global 2000 for 2008 ranked
it 317th in the world.

2012
2012

2017
2017

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

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 Headquarters
S. NO.
HEADQUARTERS
1.
NCRHQ
2.
ER HEADQUARTER-1
3.
ER HEADQUARTER-2
4.
NRHQ
5.
SR HEADQUARTER
6.
WR-1 HEADQUARTER
7.
HYDRO HEADQUARTER
8.
WR-2 HEADQUARTER

CITY
DELHI
BHUBANESHWAR
PATNA
LUCKNOW
HYDERABAD
MUMBAI
DELHI
RAIPUR

NTPC PLANTS
1. Thermal-Coal based

11

S. NO.

CITY

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
TOTAL

STATE

SINGRAULI
KORBA
RAMAGUNDAM
FARAKKA
VINDHYACHAL
RIHAND
KAHALGAON
DADRI
TALCHER
UNCHAHAR
TALCHER
SIMHADRI
TANDA
BADARPUR
SIPAT
SIPAT
BONGAIGAON
MOUDA
RIHAND
BARH

INSTALLED

UTTAR PRADESH
CHATTISGHAR
ANDHRA PRADESH
WEST BENGAL
MADHYA PRADESH
UTTAR PRADESH
BIHAR
UTTAR PRADESH
ORISSA
UTTAR PRADESH
ORISSA
ANDHRA PRADESH
UTTAR PRADESH
DELHI
CHHATTISGHAR
CHHATTISGHAR
ASSAM
MAHARASHTRA
UTTAR PRADESH
BIHAR

CAPACITY(MW)
2000
2600
2600
2100
3260
2500
2300
1820
3000
1050
460
1500
440
705
2320
1980
750
1000(2*500MW)
2*500MW
3300(5*660)
31495MW

2. COAL BASED (Owned by JVs)
S.NO.
1.
2.
3.
4.
5.
6.
TOTAL

NAME OF THE
JV
NSPCL
NSPCL
NSPCL
NPGC
M.T.P.S.
BRBCL

CITY
DURGAPUR
ROURKELA
BHILAI
AURANGABAD
KANTI
NABINAGAR

STATE

INSTALLED

WEST BENGAL
ORISSA
CHHATTISGHAR
BIHAR
BIHAR
BIHAR

CAPACITY(MW)
120
120
574
1980
110
1000
3904MW

3. GAS Based
12

S.NO.
1.
2.
3.
4.
5.
6.
7.
TOTAL

CITY
ANTA
AURAIYA
KAWAS
DADRI
JHANOR
KAYAMKULAM
FARIDABAD

STATE

INSTALLED

RAJSTHAN
UTTAR PRADESH
GUJARAT
UTTAR PRADESH
GUJARAT
KERALA
HARYANA

CAPACITY(MW)
419
652
645
817
648
350
430
3995MW

NTPC HYDEL
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
13

(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 GOALS
The 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.

POWER BURDEN
India, 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 SYSTEM
Driven 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.

14

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 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.

15

POLLUTION CONTROL SYSTEMS
While 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
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 LowNOx 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

16

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
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
17

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.
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

18

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
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

19

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 SYSTEMS
Waste Management
Various types of wastes such as Municipal or domestic wastes, hazardous wastes, BioMedical 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
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.

20

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.

OVERALL POWER GENERATION
UNIT
INSTALLED CAPACITY
GENERATION
NO. OF EMPLOYEES
GENERATION/EMPLOYEE

1997-98

MW
MUs
NO.
MUs

16,847
97,609
23,585
4.14

2006-07

% OF

26,350
1,88,674
24,375
7.74

INCREASE
56.40
93.29
3.34
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-

99-

00-

01-

02-03

03-04

04-05

05-06

06-07

GENERATIO

98
106.

99
109.

00
118.

01
130.

02
133.

140.8

149.1

159.1

170.8

188.6

N BU

2

5

7

1

2

6

6

1

8

7
21

PL %

75.2

76.6

80.3

81.8

81.1

83.60

84.40

87.51

87.54

89.43

AVAILABILIT

0
85.0

0
89.3

9
90.0

0
88.5

0
81.8

88.70

88.80

91.20

89.91

90.09

Y FACTOR

3

6

6

4

0

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 STATION
COUNTRY
LOCATION
STATUS
COMISSION DATE

INDIA
MATHURA ROAD, BADARPUR, NEW DELHI
ACTIVE
1973
22

OPERATOR(S)

NTPC

POWER STATION INFORMATION
PRIMARY FUEL
GENERATION UNITS

COAL-FIRED
5

POWER GENERATION INFORMATION
INSTALLED CAPACITY

705.00 MW

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,

23

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
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

24

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.

25

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

28

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 DATA
Rated 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
cm/hour

27000

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

OPERATION
THERMAL 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

29

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

30

16. Bottom ash hoper
17. Super heater
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

31

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.

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.
32

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.
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

33

pressure drop, which results in the rotation of the turbine shaft. The turbine shaft is
connected to a generator, which produces the electrical energy.

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
34

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.

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

35

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 noncorrosive. A dearator typically includes a vertical domed deaeration section as the
deaeration boiler feed water tank. A Steam generating boiler requires that the
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

36

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.

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;

37

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.
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.

38

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 coalfired boiler application.
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

39

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.

CHAPTER-3
EMD- I
Electrical Maintenance Division I
It is responsible for the maintenance of:

HT/LT MOTORS TURBINE & BOILER SIDE
Boiler 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.

40

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.

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

41

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

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
42

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
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.

43

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.
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.
44

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
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
45

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

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

46

14A, 14B
15A, 15B
16A, 16B
17A, 17B
18A, 18B
4. Transfer Point 6
5. Breaker House
6. Rejection House
7. Reclaim House
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
47

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 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.
48

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
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

49

· 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.

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
50

· 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
· 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

51

· 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

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.

52

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. 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.

53

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
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

54

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.

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 grain55

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
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

56

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,
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.
57

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 40 0C.
Rating of 95 MW GeneratorManufacture 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

Frequency

- 50 Hz

Stator winding connection

- 3 phase

Rating of 210 MW GeneratorManufacture by Bharat heavy electrical Limited (BHEL)
Capacity

- 247000 KVA

Voltage (stator)

- 15750 V

Current (stator)

- 9050 A

Voltage (rotor)

- 310 V

58

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

Transformer
A 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
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

59

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

CHAPTER-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.

60

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

Figure 12: CONTROL UNIT

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
61

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.

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

Through Water
Walls It Goes Up

Boiler Feed Pump

Furnace

Fire

High Pressure
Heater &
Economizer

Bottom Ring
Header

Water

Drum

Steam + Water

Valves

Drum

Down Comer

(Steam + Water)

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 asi)

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.

63

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 logici)

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:
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.

64

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.

65

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.
If boundary limits are reached as full open or full close then on giving any further
command will not be executed by the motor.

66

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.

CIRCUIT DIAGRAM
67

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
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

68

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

69

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 noninverting 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

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.

70

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
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

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