project report_thermal power plant

7/31/2019 PROJECT REPORT_thermal Power Plant

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PROJECT REPORT ( N.T.P.C.

BADARPUR, NEW DELHI )

INDUSTRIAL TRAINING REPORT

(SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIRMENT OF THE

COURSE OF B.TECH.)

UNDERTAKEN AT

N.T.P.C. BADARPUR, NEW DELHI FROM: 18th JUNE to 11th August, 2007

SUBMITTED TO: SUBMITTED BY:

Mrs. RACHNA SINGH Ashutosh Kumar

N.T.P.C. Badarpur B.Tech 3rd Year

Electrical Engineering

JSS ACADEMY OF TECHNICAL EDUCATION (NOIDA)

TABLE OF CONTENT

Certificate Acknowledgement

Training at BTPS

1. Introduction

NTPC

Badarpur Thermal Power Station

2. Operation

3. Control & Instrumentation

Manometry Lab

Protection and interlock Lab

Automation Lab

Water Treatment Plant

Furnace Safeguard Supervisory System

Electronic Test Lab

4. Electrical Maintenance Division-I

HT/LT Switch Gear

HT/LT Motors, Turbine & Boilers Side

CHP/NCHP

5. Electrical Maintenance Division-II


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Generator

Transformer & Switchyard

Protection

Lighting

EP CERTIFICATE

This is to certify that------------------------- student of Batch Electrical & Electronics Branch

IIIrd Year; Sky line Institute of Engineering & Technology Noida has successfully

completed his industrial training at Badarpur Thermal power station New Delhi for eight

week from 18th June to 11th august 2007

He has completed the whole training as per the training report submitted by him.

Training Incharge

BTPS/NTPC

NEW DELHI

Acknowledgement

With profound respect and gratitude, I take the opportunity to convey my thanks to

complete the training here.

I do extend my heartfelt thanks to Mrs. Rachna Singh for providing me this opportunity to

be a part of this esteemed organization.

I am extremely grateful to all the technical staff of BTPS/NTPC for their co-operation and

guidance that helped me a lot during the course of training. I have learnt a lot working


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under them and I will always be indebted of them for this value addition in me.

I would also like to thank the training in charge of Skyline Institute of Engineering &

Technology Gr. Noida and all the faculty member of Electrical & Electronics department

for their effort of constant co-operation. Which have been significant factor in the

accomplishment of my industrial training.

Training at BTPS

I was appointed to do eight-week training at this esteemed organization from 18th June to

11th august 2007. In these eight weeks I was assigned to visit various division of the plant

which were

1. Operation2. Control and instrumentation (C&I)3. Electrical maintenance division I (EMD-I)4. Electrical maintenance division II (EMD-II)

This eight-week training was a very educational adventure for me. It was really amazing tosee the plant by your self and learn how electricity, which is one of our daily requirements

of life, is produced.

This report has been made by self-experience at BTPS. The material in this report has been

gathered from my textbooks, senior student report, and trainer manual provided by

training department. The specification & principles are at learned by me from the

employee of each division of BTPS.


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ABOUT NTPC

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%. With in 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.

POWER GENERATION IN INDIA


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NTPCs 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 ofDurgapur (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.

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

construction andoperations. Its providing power at the cheapest average tariff in the

country..

NTPC is committed to theenvironment, 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 3c.

NTPC has also taken proactive steps forash utilization. In 1991, it set up Ash Utilization

Division

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

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

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

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 itsRehabilitation and

Resettlementprogrammes, 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.
http://www.ntpc.co.in/operations/operations.shtmlhttp://www.ntpc.co.in/operations/operations.shtmlhttp://www.ntpc.co.in/operations/operations.shtmlhttp://www.ntpc.co.in/infocus/environment.shtmlhttp://www.ntpc.co.in/infocus/environment.shtmlhttp://www.ntpc.co.in/infocus/environment.shtmlhttp://www.ntpc.co.in/infocus/ashutilisation.shtmlhttp://www.ntpc.co.in/infocus/ashutilisation.shtmlhttp://www.ntpc.co.in/infocus/ashutilisation.shtmlhttp://www.ntpc.co.in/otherlinks/cenpeep.shtmlhttp://www.ntpc.co.in/otherlinks/cenpeep.shtmlhttp://www.ntpc.co.in/otherlinks/cenpeep.shtmlhttp://www.ntpc.co.in/infocus/socialcomm.shtmlhttp://www.ntpc.co.in/infocus/socialcomm.shtmlhttp://www.ntpc.co.in/infocus/socialcomm.shtmlhttp://www.ntpc.co.in/infocus/socialcomm.shtmlhttp://www.ntpc.co.in/infocus/socialcomm.shtmlhttp://www.ntpc.co.in/infocus/socialcomm.shtmlhttp://www.ntpc.co.in/otherlinks/cenpeep.shtmlhttp://www.ntpc.co.in/infocus/ashutilisation.shtmlhttp://www.ntpc.co.in/infocus/environment.shtmlhttp://www.ntpc.co.in/operations/operations.shtml


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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.

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.

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 approvedby 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.

Environment Management, Occupational Health and Safety Systems:

NTPC has actively gone for adoption of best international practices on environment,

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

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

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

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

18001 by reputed national and international Certifying Agencies.

Pollution Control 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 (ESPs) and particulate emission is controlled well within the stipulated

norms. The ash collected in the ESPs is disposed to Ash Ponds in slurry form.

Flue Gas Stacks:


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

(SOX, NOX etc) into the atmosphere.

Low-NOXBurners:

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

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

Neutralisation Pits:Neutralisation pits have been provided in the Water Treatment Plant (WTP) for pH

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

further treatment and use.

Coal Settling Pits / Oil Settling Pits:

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

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

DE & DS Systems:

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

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

Handling Plant (CHP).Cooling Towers:

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

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

pollution and conservation of fresh water.

Ash Dykes & Ash Disposal systems:

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

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

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

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

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

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

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

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

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

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

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

system.

Ash Water Recycling System:

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

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

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

water requirements for transportation of ash from the plant.

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

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

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

required as make-up water for disposal of ash.

Dry Ash Extraction System (DAES):

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

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


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

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

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

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

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

and their appropriate treatment centrally and re-circulation of the treated effluent for

various plant uses.

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

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

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

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

Sewage Treatment Plants & Facilities:

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

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

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

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

quality. The effluent quality is monitored regularly and treated effluent conforming to the

prescribed limit is discharged from the station. At several stations, treated effluents of

STPs are being used for horticulture purpose.

Environmental Institutional Set-up:

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

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

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

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

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

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

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

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

the individual station.

Environment Reviews:

To maintain constant vigil on environmental compliance, Environmental Reviews are

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

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

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

Such periodic Environmental Reviews and extensive monitoring of the facilities carried out

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

of the Air and Water Consents.


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Up gradation & retrofitting of Pollution Control Systems:

Waste Management

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

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

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

waste oils, grease, lead acid batteries, other lead bearing wastes (such as garkets etc.), oil &clarifier sludge, used resin, used photo-chemicals, asbestos packing, e-waste, metal scrap,

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

(bio-degradable) wastes, buidling material wastes, silica gel, glass wool, fused lamps &

tubes, fire resistant fluids etc. These wastes fall either under hazardous wastes category or

non-hazardous wastes category as per classification given in Government of Indias

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

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

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

Steam Generators employing super critical steam parameters have already been

implemented as a green field project.

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

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

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

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

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

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

as compared to conventional plants.

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

all concerned to keep the pollution under control and preserve the health and quality of the

natural environment in the vicinity of the power stations. NTPC is committed to provide

affordable and sustainable power in increasingly larger quantity. NTPC is conscious of its

role in the national endeavour of mitigating energy poverty, heralding economic prosperity

and thereby contributing towards Indias emergence as a major global economy.

Lay out of Employees


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Overall Power Generation

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

years.

The energy conservation parameters like specific oil consumption and auxiliary power

consumption have also shown considerable improvement over the years.

ABOUT BADARPUR THERMAL POWER STATION

Unit 1997-98 2006-07 % of increase

Installed Capacity MW 16,847 26,350 56.40

Generation MUs 97,609 1,88,674 93.29

No. of employees No. 23,585 24,375 3.34

Generation/employee MUs 4.14 7.74 86.95

OPERATIONAL PERFORMANCE OF COAL BASED NTPC STATIONSUnit 97-98 98-99 99-00 00-01 01-02 02-03 03-04 04-05 05-06 06-07

Generation BU 106.2 109.5 118.7 130.1 133.2 140.86 149.16 159.11 170.88 188.67

PLF % 75.20 76.60 80.39 81.8 81.1 83.6 84.4 87.51 87.54 89.43

Availability

Factor% 85.03 89.36 90.06 88.54 81.8 88.7 88.8 91.20 89.91 90.09


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I was assigned to do training in operation division from 18th June 2007 to 23rd June 2007

ELECTRICITY FROM COAL

Coal from the coal wagons is unloaded with the help of wagon tipplers in the C.H.P. this

coal is taken to the raw coal bunkers with the help of conveyor belts. Coal is then

transported to bowl mills by coal feeders where it is pulverized and ground in the powered

form.

This crushed coal is taken away to the furnace through coal pipes with the help of hot andcold mixture P.A fan. This fan takes atmospheric air, a part of which is sent to pre heaters

while a part goes to the mill for temperature control. Atmospheric air from F.D fan in the

air heaters and sent to the furnace as combustion air.

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

Water from the drum passes through the 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 density difference the water rises up in the water wall tubes. This steam and water

mixture is again taken to the boiler drum where the steam is sent to super heaters for super

heating. The super heaters are located inside the furnace and the steam is super heated

(540 degree Celsius) and finally it goes to the turbine.

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

balance draft in the furnace with F.D fan. These fuel gases heat energy to the various super

heaters and finally through air pre heaters and goes to electrostatic precipitators where the

ash particles are extracted. This ash is mixed with the water to from slurry is pumped to

ash period.

The steam from boiler is conveyed to turbine through the steam pipes and through stop

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

valves and controls valves are located in steam chest and governor driven from main

turbine shaft operates the control valves the amount used.

Steam from controlled valves enter high pressure cylinder of turbines, where it passes

through the ring of blades fixed to the cylinder wall. These act as nozzles and direct the

steam into a second ring of moving blades mounted on the disc secured in the turbine shaft.

The second ring turns the shaft as a result of force of steam. The stationary and moving

blades together.


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MAIN GENERATOR

MAIN TURBINE DATA

Maximum continuous KVA rating 24700KVA

Maximum continuous KW 210000KWRated terminal voltage 15750V

Rated Stator current 9050 A

Rated Power Factor 0.85 lagExcitation current at MCR Condition 2600 A

Slip-ring Voltage at MCR Condition 310 V

Rated Speed 3000 rpmRated Frequency 50 Hz

Short circuit ratio 0.49

Efficiency at MCR Condition 98.4%

Direction of rotation viewed Anti Clockwise

Phase Connection Double StarNumber of terminals brought out 9( 6 neutral and 3 phase)

Rated output of Turbine 210 MW

Rated speed of turbine 3000 rpmRated pressure of steam before emergency 130 kg/cm^2

Stop valve rated live steam temperature 535 degree Celsius

Rated steam temperature after reheat at inlet to receptor valve 535 degree CelsiusSteam flow at valve wide open condition 670 tons/hour


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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 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 diagram of a coal fired thermal power station

1. Cooling water pump

2. Three-phase transmission line

3. Step up transformer

Rated quantity of circulating water through condenser 27000 cm/hour

1. For cooling water temperature (degree Celsius) 24,27,30,331.Reheated steam pressure at inlet of interceptor valve in

kg/cm^2 ABS23,99,24,21,24,49,24.82

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


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4. Electrical Generator

5. Low pressure steam

6. Boiler feed water pump

7. Surface condenser

8. Intermediate pressure steam turbine

9. Steam control valve10. High pressure steam turbine

11. Deaerator Feed water heater

12. Coal conveyor

13. Coal hopper

14. Coal pulverizer

15. boiler steam drum

16. Bottom ash hoper

17. Super heater

18. Forced draught(draft) fan

19. Reheater

20. Combustion air intake21. 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 tower use evaporation of water to

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

Chemical plants, power plants and building cooling, for example. The tower vary in size

from small roof-top units to very large hyperboloid structures that can be up to 200 meters

tall and 100 meters in diameter, or rectangular structure that can be over 40 meters tall

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

constructed on site.

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

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

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

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

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

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

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,


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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 starconnected with the standard mains voltage being the phase-neutral voltage. Another system

commonly seen in North America is to have a delta connected secondary with a center tap

on one of the windings supplying the ground and neutral. This allows for 240 V three phase

as well as three different single phase voltages( 120 V between two of the phases and

neutral , 208 V between the third phase ( known as a wild leg) and neutral and 240 V

between any two phase) to be available from the same supply.

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 station use large stem turbines driving electric generators to produce most

(about 86%) of the worlds 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


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

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

the potential energy of the steam into kinetic energy into forces, caused by pressure drop,

which results in the rotation of the turbine shaft. The turbine shaft is connected to a

generator, which produces the electrical energy.

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.

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 waterinto the boiler; the pump must generate sufficient pressure to overcome the steam pressure

developed by the boiler. This is usually accomplished through the use of a centrifugal

pump.

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

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

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

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

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

its discharge is blocked); the second stage will be triggered. This stage may switch off the

boiler equipment (preventing the boiler from running dry and overheating), trigger an

alarm, or both.

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.


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6. Control valves

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

conditions such as temperature,pressure,flow,and liquid Level by fully partially opening or

closing in response to signals received from controllers that compares a set point to a

process variable whose value is provided by sensors that monitor changes in suchconditions. The opening or closing of control valves is done by means of electrical,

hydraulic or pneumatic systems

7. Deaerator

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

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

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

deaeration boiler feed water tank. A Steam generating boiler requires that the 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 themetal. 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.[4]

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 irreversibilitys associated with heat transfer to the working fluid

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

conveyor Beltthat rotates about them. The pulleys are powered, moving the belt and the

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

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

9. Pulverizer

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

plant.


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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 indensities between hot and cold water helps in the accumulation of the hotter-water/and

saturatedsteam into steam drum. Made from high-grade steel (probably stainless) and its

working involves temperatures 390C and pressure well above 350psi (2.4MPa). The

separated steam is drawn out from the top section of the drum. Saturated steam is drawn

off the top of the drum. The steam will re-enter the furnace in through a super heater,

while the saturated water at the bottom of steam drum flows down to the mud-drum /feed

water drum by down comer tubes accessories include a safety valve, water level indicator

and fuse plug. A steam drum is used in the company of a mud-drum/feed water drum

which is located at a lower level. So that it acts as a sump for the sludge or sediments which

have a tendency to the bottom.

11. Super Heater

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

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

inside the engine. Super heaters increase the efficiency of the steam engine, and were

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

steam; non-superheated steam is called saturated steam or wet steam; Super heaters were

applied to steam locomotives in quantity from the early 20th century, to most steam

vehicles, and so stationary steam engines including power stations.

12. Economizers

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

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

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

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

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

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

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 Greens 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


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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 ofthe ducting and the flue gas stack. It also allows control over the temperature of gases

leaving the stack.

14. Precipitator

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

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

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

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

ESPs continue to be excellent devices for control of many industrial particulate emissions,

including smoke from electricity-generating utilities (coal and oil fired), salt cake collectionfrom black liquor boilers in pump mills, and catalyst collection from fluidized bed catalytic

crackers from several hundred thousand ACFM in the largest coal-fired boiler application.

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. Transformerrectifier 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 ESPs to stay in operation

for years at a time.

15. Fuel gas stack

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

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

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

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

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

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

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

more, so as to disperse the exhaust pollutants over a greater aria and thereby reduce the

concentration of the pollutants to the levels required by governmental environmental

policies and regulations.

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

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


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C&I

(CONTROL AND INSTRUMENTATION)

I was assigned to do training in control and instrumentation from 25th June 2007 to 14th

July 2007

CONTROL AND INSTRUMENTATION

This division basically calibrates various instruments and takes care of any faults occur in

any of the auxiliaries in the plant.

It has following labs:

1. MANOMETRY LAB2. PROTECTION AND INTERLOCK LAB3. AUTOMATION LAB4. WATER TREATEMENT LAB5. FURNACE SAFETY SUPERVISORY SYSTEM(FSSS)6. ELECTRONICS TEST LAB

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


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the electronic computation chipsets and recorders and lastly the controlling circuitry, all fallunder this.

5.0 MANOMETRY LAB

5.0.1 TRANSMITTERSIt is used for pressure measurements of gases and liquids, its working principle is that the

input pressure is converted into electrostatic capacitance and from there it is conditioned andamplified. It gives an output of 4-20 ma DC. It can be mounted on a pipe or a wall. For liquid

or steam measurement transmitters is mounted below main process piping and for gas

measurement transmitter is placed above pipe.

5.0.2 MANOMETER

Its a tube which is bent, in U shape. It is filled with a liquid. This device corresponds to a

difference in pressure across the two limbs.

5.0.3 BOURDEN PRESSURE GAUGE

Its an oval section tube. Its one end is fixed. It is provided with a pointer to indicate the

pressure on a calibrated scale. It is of 2 types:

(a) Spiral type: for Low pressure measurement.

(b) Helical Type: for High pressure measurement.

5.1 PROTECTION AND INTERLOCK LAB

5.1.1 INTERLOCKING

It is basically interconnecting two or more equipments so that if one equipments fails other

one can perform the tasks. This type of interdependence is also created so that equipments

connected together are started and shut down in the specific sequence to avoid damage.

For protection of equipments tripping are provided for all the equipments. Tripping can be

considered as the series of instructions connected through OR GATE. When a fault occurs

and any one of the tripping is satisfied a signal is sent to the relay, which trips the circuit.

The main equipments of this lab are relay and circuit breakers. Some of the instrument

uses for protection are:

1. RELAY

It is a protective device. It can detect wrong condition in electrical circuits by constantly

measuring the electrical quantities flowing under normal and faulty conditions. Some of

the electrical quantities are voltage, current, phase angle and velocity.

2. FUSES

It is a short piece of metal inserted in the circuit, which melts when heavy current flows


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through it and thus breaks the circuit. Usually silver is used as a fuse material because:

a) The coefficient of expansion of silver is very small. As a result no critical fatigue occurs

and thus the continuous full capacity normal current ratings are assured for the long time.

b) The conductivity of the silver is unimpaired by the surges of the current that produces

temperatures just near the melting point.

c) Silver fusible elements can be raised from normal operating temperature to vaporizationquicker than any other material because of its comparatively low specific heat.

5.1.2 MINIATURE CIRCUIT BREAKER

They are used with combination of the control circuits to.

a) Enable the staring of plant and distributors.

b) Protect the circuit in case of a fault.

In consists of current carrying contacts, one movable and other fixed. When a fault occursthe contacts separate and are is stuck between them. There are three types of

- MANUAL TRIP

- THERMAL TRIP

- SHORT CIRCUIT TRIP

5.1.3 ROTECTION AND INTERLOCK SYSTEM

1. HIGH TENSION CONTROL CIRCUIT

For high tension system the control system are excited by separate D.C supply. For starting

the circuit conditions should be in series with the starting coil of the equipment to energize

it. Because if even a single condition is not true then system will not start.

2. LOW TENSION CONTROL CIRCUIT

For low tension system the control circuits are directly excited from the 0.415 KV A.C

supply. The same circuit achieves both excitation and tripping. Hence the tripping coil is

provided for emergency tripping if the interconnection fails.


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5.2 AUTOMATION LAB

This lab deals in automating the existing equipment and feeding routes.

Earlier, the old technology dealt with only (DAS) Data Acquisition System and came to be

known as primary systems. The modern technology or the secondary systems are coupled

with (MIS) Management Information System. But this lab universally applies the pressure

measuring instruments as the controlling force. However, the relays are also provided butthey are used only for protection and interlocks.

Once the measured is common i.e. pressure the control circuits can easily be designed with

single chips having multiple applications. Another point is the universality of the supply,

the laws of electronic state that it can be any where between 12V and 35V in the plant. All

the control instruments are excited by 24V supply (4-20mA) because voltage can be

mathematically handled with ease therefore all control systems use voltage system for

computation. The latest technology is the use of ETHERNET for control signals. 5.3

PYROMETER LAB

(1) LIQUID IN GLASS THERMOMETER

Mercury in the glass thermometer boils at 340 degree Celsius which limits the range of

temperature that can be measured. It is L shaped thermometer which is designed to reachall inaccessible places.

(2) ULTRA VIOLET CENSOR

This device is used in furnace and it measures the intensity of ultra violet rays there and

according to the wave generated which directly indicates the temperature in the furnace.

(3) THERMOCOUPLES

This device is based on SEEBACK and PELTIER effect. It comprises of two junctions at

different temperature. Then the emf is induced in the circuit due to the flow of electrons.

This is an important part in the plant.

(4) RTD (RESISTANCE TEMPERATURE DETECTOR)

It performs the function of thermocouple basically but the difference is of a resistance. In

this due to the change in the resistance the temperature difference is measured.

In this lab, also the measuring devices can be calibrated in the oil bath or just boiling water

(for low range devices) and in small furnace (for high range devices). 5.4 FURNACE

SAFETY AND SUPERVISORY SYSTEM LABThis lab has the responsibility of starting fire in the furnace to enable the burning of coal.

For first stage coal burners are in the front and rear of the furnace and for the second and

third stage corner firing is employed. Unburnt coal is removed using forced draft or

induced draft fan. The temperature inside the boiler is 1100 degree Celsius and its height is

18 to 40 m. It is made up of mild steel. An ultra violet sensor is employed in furnace to

measure the intensity of ultra violet rays inside the furnace and according to it a signal in

the same order of same mV is generated which directly indicates the temperature of the

furnace.

For firing the furnace a 10 KV spark plug is operated for ten seconds over a spray of diesel

fuel and pre-heater air along each of the feeder-mills. The furnace has six feeder mills each

separated by warm air pipes fed from forced draft fans. In first stage indirect firing is

employed that is feeder mills are not fed directly from coal but are fed from three feeders


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but are fed from pulverized coalbunkers. The furnace can operate on the minimum feed

from three feeders but under not circumstances should any one be left out under operation,

to prevent creation of pressure different with in the furnace, which threatens to blast it.

5.5 ELECTRONICS LAB

This lab undertakes the calibration and testing of various cards. It houses various types of

analytical instruments like oscilloscopes, integrated circuits, cards auto analyzers etc.

Various processes undertaken in this lab are:

1. Transmitter converts mV to mA.

2. Auto analyzer purifies the sample before it is sent to electrodes. It extracts the magnetic

portion.

5.6 ANNUNCIATIN CARDS

They are used to keep any parameter like temperature etc. within limits. It gets a signal if

parameter goes beyond limit. It has a switching transistor connected to relay that helps in

alerting the UCB.

39. Control and Instrumentation Control and Instrumentation

Measuring Instrumentsments

In any process the philosophy of instrumentation should provide a comprehensive

intelligence feed back on the important parameters viz. Temperature, Pressure, Level and

Flow. This Chapter Seeks to provide a basic understanding of the prevalent instruments

used for measuring the above parameters.

Temperature Measurement

The most important parameter in thermal power plant is temperature and its

measurement plays a vital role in safe operation of the plant. Rise of temperature in a

substance is due to the resultant increase in molecular activity of the substance on

application of heat; which increases the internal energy of the material. Therefore there

exists some property of the substance, which changes with its energy content. The change

may be observed with substance itself or in a subsidiary system in thermodynamic

equilibrium, which is called testing body and the system itself is called the hot body.

Expansion Thermometer

Solid Rod Thermometers a temperature sensing - Controlling device may be designed

incorporating in its construction the principle that some metals expand more than others


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for the same temperature range. Such a device is the thermostat used with water heaters

(Refer Fig. 69).


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Fig No.-69 Rod Type Thermostat

The mercury will occupy a greater fraction of the volume of the container than it will at alow temperature.

Under normal atmospheric conditions mercury normally boils at a temperature of (347C).

To extend the range of mercury in glass thermometer beyond this point the top end of a

thermometer bore opens into a bulb which is many times larger in capacity than the bore.

This bulb plus the bore above the mercury, is then filled with nitrogen or carbon dioxide

gas at a sufficiently high pressure to prevent boiling at the highest temperature to which

the thermometer may be used.

Mercury in Steel the range of liquid in glass thermometers although quite large, does not

lend itself to all industrial practices. This fact is obvious by the delicate nature of glass also

the position of the measuring element is not always the best position to read the result.

Types of Hg in Steel Thermometers are:

Bourdon TubeMost common and simplest type (Refer Fig. 71)

Spiral typeMore sensitive and used where compactness is necessary

Helical TypeMost sensitive and compact. Pointer may be mounted direct on end of helix

Which rotates, thus eliminating backlash and lost motion?

Linkages, which only allow the pointer to operate over a selected range of pressure toeither side of the normal steam pressure. (Refer Fig No.77)

Dewrance Critical Pressure Gauge Measurement of Level

Direct Methods

'Sight Glass' is used for local indication on closed or open vessels. A sight glass is a tube of

toughened glass connected at both ends through packed unions and vessel. The liquid level

will be the same as that in the vessel. Valves are provided for isolation and blow down.

"Float with Gauge Post" is normally used to local indication on closed or open vessels.

"Float Operated Dial" is used for small tanks and congested areas. The float arm isconnected to a quadrant and pinion which rotates the pointer over a scale.


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Bourden Pressure Gauge a Bourdon pressure gauge calibrated in any fact head is often

connected to a tank at or near the datum level.

"Mercury Manometer" is used for remote indication of liquid level. The working principle

is the same as that of a manometer one limp of a U-tube is connected to the tank, the other

being open to atmosphere. The manometer liquid must not mix with the liquid in the vessel,

and where the manometer is at a different level to the vessel, the static head must be

allowed in the design of the manometer.

'Diaphragm Type' is used for remote level indication in open tanks or docks etc. A pressure

change created by the movement of a diaphragm is proportional to a change in liquid level

above the diaphragm. This consists of a cylindrical box with a rubber or plastic diaphragm

across its open end as the level increases .the liquid pressure on the diaphragm increases


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and the air inside is compressed. This pressure is transmitted via a capillary tube to an

indicator or recorder incorporating a pressure

Measuring element.

Sealed Capsule Type The application and principle is the same as for the diaphragm box.

In this type, a capsule filled with an inert gas under a slight pressure is exposed to thepressure due to the head of liquid and is connected by a capillary to an indicator. In some

cases the capsule is fitted external to the tank and is so arranged that it can be removed

whilst the tank is still full, a spring loaded valve automatically shutting off the tapping

point.

Air Purge System This system provides the simplest means of obtaining an indication of

level, or volume, at a reasonable distance and above or below, the liquid being measured.

The pressure exerted inside an open ended tube below the surface of a liquid is

proportional to the depth of the liquid

The Measurement of Flow

Two principle measurements are made by flow meters viz. quantity of flow and rate of

flow. 'Quantity of flow' is the quantity of fluid passing a given point in a given time, i.e.

gallons or pounds. Rate of flow' is the speed of. a fluid passing a given point at a given


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instant and is proportional to quantity passing at a given instant, i.e. gallons per minute or

pounds per hour. There are two groups of measuring devices: -

Positive, or volumetric, which measure flow by transferring a measured quantity of fluid

from the inlet to the outlet.

Inferential, which measures the velocity of the flow and the volume passed is inferred, it

being equal to the velocity times the cross sectional area of the flow. The inferential type is

the most widely used.

Measurement of Fluid Flow through Pipes:

"The Rotating Impeller Type" is a positive type device which is used for medium quantity

flow measurement i.e., petroleum and other commercial liquids. It consists of

Two fluted rotors mounted in a liquid tight case fluid flow and transmitted to a counter.

Rotating Oscillating Piston Type This is also a positive type device and is used for

measuring low and medium quantity flows, e.g. domestic water supplies. This consists of a

brass meter body into which is fitted a machined brass working chamber and cover,

containing a piston made of ebonite. This piston acts as a moving chamber and transfers a

definite volume of fluid from the inlet to the outlet for each cycle.

Helical Vane Type For larger rates of flow, a helical vane is mounted centrally in the body

of the meter. The helix chamber may be vertical or horizontal and is geared to a counter.

Usually of pipe sizes 3" to 10" Typical example is the Kent Torrent Meter.

Turbine Type this like the helical Vane type is a inference type of device used for

large flows with the minimum of pressure drop. This consists of a turbine or drum

revolving in upright bearings, retaining at the top by a collar. Water enters the drum

from the top and leaves tangentially casings to rotate at a speed dependent upon the

quantity of water passed. The cross sectional area of the meter throughout is equal to

the area of the inlet and outlet pipes and is commonly used on direct supply water

mains,

Combination Meters this is used for widely fluctuating flows. It consists of a larger

meter (helical, turbine or fan) in the main with a small rotary meter or suitable type in a

bypass. Flow is directed into either the main or bypass according to the quantity of flow

by an automatic valve. By this means flows of 45 to 40,000 gallons per hour can be

measured.

Measurement of Fluid Flow through Open Channels:

The Weir If a fluid is allowed to flow over a square weir of notch, The height of the liquid

above the still of the weir, or the bottom of the notch will be a measure of the rate of flow.


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A formula relates the rate of flow to the height and is dependent upon the design of the

Venturi Flumes The head loss caused by the weir flow meter is considerable and its

construction is sometimes complicated, therefore the flume is sometimes used. The

principle is same as that of venture except that the rate of flow is proportional to the

depth of the liquid in the upstream section. It consists of a local contraction in the cross

section of flow through a channel in the shape of a venturi. It is only necessary to

measure the depth of the upstream section which is a measure of the rate of flow. This

may be done by pressure tapping at the datum point or by a float in an adjacent level

chamber.

Pressure Difference Flow meters These are the most widely used type of flow meter since

they are capable of measuring the flow of all industrial fluids passing through pipes. They

consists of a primary element inserted in the pipeline which generates a differential

pressure, ^he magnitude of which is proportional to the square of the rate of flow and a

secondary element which measures this differential pressure and translates it into terms of

flow. (Refer fig. 79).

Fig. No-79 Pressure Differential Flow meters

Primary elements Bernoulli's theorem states that the quantity of fluid or gas flowing is

proportional to the square root of the differential pressure. There are four principal types

of primary elements (or restrictions) as enumerate below:

Venturi; This is generally used for medium and high quantity fluid flow and it consists of


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two hollow truncated cones, the smaller diameters of which are connected together by a

short length of parallel pipe, the smallest diameter of the tube formed by this length of

parallel pipe is known as the throat section and the lower of the two pressures, (the throat,

or downstream pressure) is measured here.

Orifice Plate This is the oldest and most common form of pressure differential device. In its

simplest form it consists of a thin metal plate with a central hold clamped between two pipeflanges. In the metering of dirty fluids or fluids containing solids the hole is placed so that

its lower edge coincides with the inside bottom of the pipe. (Refer Fig.80) It is essential that

the leading edge of the hole is absolutely sharp rounding or burring would have a very

marked effect on the flow.

Fig No.-80 Typical Orifice Plate Pressure Tapping

EMD I

Electrical Maintenance division I


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I was assigned to do training in Electrical maintenance division I from 17th July 2007 to

28th July 2007.

This two week of training in this division were divided as follows.

17th to 19th July 2007- HT/LT switchgear

21st to 24th July 2007 - HT/LT Motors, Turbine &Boiler side

26th to 28th July 2007- CHP/NCHP Electrical

Electrical maintenance division 1

It is responsible for maintenance of:

1. Boiler side motors

2. Turbine side motors

3. Outside motors

4. Switchgear

1. Boiler side motors:

For 1, units 1, 2, 3

1.1D Fans 2 in no.

2.F.D Fans 2 in no.

3.P.A.Fans 2 in no.

4.Mill Fans 3 in no.

5.Ball mill fans 3 in no.

6.RC feeders 3 in no.

7.Slag Crushers 5 in no.

8.DM Make up Pump 2 in no.


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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 and Phosphorous Dozing 2 in no.

2/3 in no.

1. COAL HANDLING PLANT (C.H.P)

2. 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.

Major Components

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

The process is performed by a slipring motor of rating: 55 KW, 415V, 1480 RPM. This

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

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

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

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

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

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

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

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

have a capacity of carrying coal at the rate of 400 tons per hour. Few conveyors are double

belt, this is done for imp. Conveyors so that if a belt develops any problem the process is

not stalled. The conveyor belt has a switch after every 25-30 m on both sides so stop the belt

in case of emergency. The conveyors are 1m wide, 3 cm thick and made of chemically

treated vulcanized rubber. The max angular elevation of conveyor is designed such as

never to exceed half of the angle of response and comes out to be around 20 degrees.


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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 thecrusher 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 frequentclogging. NCHP uses a technique that crushes the larger of harder substance like metal

impurities easing the load on the magnetic separators.

MILLING SYSTEM

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

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

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

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

and aviator change.

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

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

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

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

simultaneously inside the mill.

4. Classifier:- It is an 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


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

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

Six in all and are running condition all the time.(a) ID Fans: - Located between electrostatic precipitator and chimney.

Type-radical

Speed-1490 rpm

Rating-300 KW

Voltage-6.6 KV

Lubrication-by oil

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

ignition of coal.

Type-axialSpeed-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 specificationsquirrel cage induction motor

Rating-340 KW

Voltage-6600KV

Curreen-41.7A

Speed-980 rpm

Frequency-50 Hz

No-load current-15-16 A

NCHP

1. Wagon Tippler:-


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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

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

10. Exit

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


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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 byconveyors 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.

SWITCH GEAR-

It makes or breaks an electrical circuit.

1. Isolation: - A device which breaks an electrical circuit when circuit is switched on to noload. 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.


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

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

withstand extremely heavy stress in process.

It is used for supplying power to auxiliaries with backup fuse protection. Rotary switch up

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

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

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

protecting the connected motors.

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

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

relay element.

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

all circuits breakers at large capacity air at high pressure is used which is maximum at thetime of quick tripping of contacts. This reduces the possibility of sparking. The pressure

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

HT SWITCH GEAR:-

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

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

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

operating mechanism by means of tensions but throw off spring to be provided at mouth of

the control the main current within the controlled device.

Type-HKH 12/1000c

Rated Voltage-66 KV

Normal Current-1250A

Frequency-5Hz

Breaking Capacity-3.4+KA Symmetrical

3.4+KA Asymmetrical

360 MVA Symmetrical

Operating Coils-CC 220 V/DC

FC 220V/DC

Motor Voltage-220 V/DC

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

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

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

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

It has the following advantages over OCB:-


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i. Fire hazard due to oil are eliminated.

ii. Operation takes place quickly.

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

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

Rated Voltage-6.6 KVCurrent-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 Rated Voltage-12 KV

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

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

Rated Voltage-12 KV

Supply Voltage Closing-220 V/DC


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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

EMD II

Electrical Maintenance division II

I was assigned to do training in Electrical maintenance division II from 31st July 2007 to

11th August 2007.

This two week of training in this division were divided as follows.


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31st to 2nd August 2007- Generator

4th August 2007 - Transformer &switchyard

7th August 2007 - protection 9th August2007 - Lightning

11th August 2007 - EP

Generator and Auxiliaries Generator and Auxiliaries

Generator Fundamentals 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.

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 (viz magnetic field) cut through the stator windings. This induces an

electromagnetic force (e.m.f.) in the stator windings. The magnitude of this e.m.f. is given

by the following expression.

E = 4.44 /O FN volts

0 = Strength of magnetic field in Webers.

F = Frequency in cycles per second or Hertz.

N = Number of turns in a coil of stator winding

F = Frequency = Pn/120

Where P = Number of poles

n = revolutions per second of rotor.

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

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

have 14 to 20 poles where as high speed steam turbine driven generators have generally 2


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poles. Pole rotors are used in low speed generators, because the cost advantage as well as

easier construction.

Development

The first A.C. Generator concept was enunciated by Michael Faraday in 1831. In 1889 Sir

Charles A. Parsons developed the first AC turbo-generator. Although slow speed AC

generators have been built for some time, it was not long before that the high-speed

generators made its impact.

Development contained until, in 1922, the increased use of solid forgings and improved

techniques permitted an increase in generator rating to 20MW at 300rpm. Up to the out

break of second world war, in 1939, most large generator;- were of the order of 30 to 50MW at 3000 rpm.

During the war, the development and installation of power plants was delayed and in order

to catch up with the delay in plant installation, a large number of 30 MW and 60 MW at

3000 rpm units were constructed during the years immediately following the war. The

changes in design in this period were relatively small.

In any development programme the. Costs of material and labour involved in

manufacturing and erection must be a basic consideration. Coupled very closely with

these considerations is the restriction is size and weight imposed by transport limitations.

Development of suitable insulating materials for large turbo-generators is one of the

most important tasks and need continues watch as size and ratings of machines

increase. The present trend is the use only class "B" and higher grade materials and

extensive work has gone into compositions of mica; glass and asbestos with

appropriate bonding material. An insulation to meet the stresses in generator slots must

follow very closely the thermal expansion of the insulated conductor without cracking or

any plastic deformation. Insulation for rotor is subjected to lower dielectric stress but

must withstand high dynamic stresses and the newly developed epoxy resins, glass

and/or asbestos molded in resin and other synthetic resins are finding wide

applications.

Generator component

This Chapter 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


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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

themselves. 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 thewindings generates heat but the temperature must not be allowed to become so high,

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

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

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

cause mechanical weakness. The problem is really to get the maximum amount of

copper into the windings without reducing the mechanical strength. With good design

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

it is further forged and machined. Very often a hole is bored through the centre of the

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

windings and ventilation.

Rotor winding

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

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

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

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

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

the windings out of the slots and they are contain

project report_thermal power plant

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