project report ntpc

7/31/2019 project report ntpc

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INDEX

1. Acknowledgements2. About the company2.1.NTPC group2.2.Evolution of NTPC2.3.Electricity from Coal

3. Definition of Automation4. Benefits of Automation5. Control Mechanisms6. Control & Instrumentation6.1.Manometry Lab6.2.Protection & Interlock Lab6.3.Automation Lab6.4.Pyrometry Lab6.5.Furnace Safety & Supervisory Lab

6.6.Electronics Lab

7. Ecological Monitoring Programme8. Ash Utilization9.Environment Management & safety System


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List of Figures

Fig. 1 Installed Capacity & its Growth

Fig. 2 Fortin Barometer

Fig. 3 Typical Arrangement of Bourdon Gauge

Fig. 4 Dewrance Critical Pressure Gauge

Fig. 5 Air Purge Level Measurement

Fig. 6 Rod Type Thermostat

Fig. 7 Helical Bi-Metal Strip

Fig. 8 Liquid Expansion Thermometer with C Bourden

Fig. 9 Bulb Forms

Fig.10 Thermocouple


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ABOUT THE COMPANY

Corporate Vision:

A world class integrated power major, powering Indias growth, with increasing

global presence

Core Values:

B-Business Ethics

C-Customer Focus

O-Organizational & Professional pride

M-Mutual Respect and Trust

I- Innovation & Speed

T-Total quality for Excellence

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

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

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

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

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

Within a span of 31 years, NTPC has emerged as a truly national power company,

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

Figure 1


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EVOLUTION OF NTPC

NTPC was set up in 1975 with 100% ownership by the

Government of India. In the last 30 years, NTPC has

grown into the largest power utility in India.

In 1997, Government of India granted NTPC status of

Navratna being one of the nine jewels of India, enhancing

the powers to the Board of Directors.

NTPC became a listed company with majority Government

ownership of 89.5%.

NTPC becomes third largest by Market Capitalisation of

listed companies

The company rechristened as NTPC Limited in line with its

changing business portfolio and transform itself from a

thermal power utility to an integrated power utility.

NTPC is the largest power utility in India, accounting for about 20% of Indias

installed capacity.

1975

1997

2005

2004


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NTPC Limited

Subsidiaries

Joint Ventures

NTPC Vidyut Vyapar

Nigam Limited

100%

NTPC Electric Supply

Co. Limited

100%

Pipavav Power

Development Co. Ltd

100%

NTPC Hydro

Limited

100%

Utility Powertech

Limited

50%

NTPC Alstom Power

Services Pvt. Limited

50%

Bhilai Electric Supply

Co. Pvt. Limited

50%

NTPC-SAIL Power

Company Pvt. Limited

50%

Ratnagiri Gas &

Power Private Ltd

28.33%

PTC India Limited

8%

NTPC Tamilnadu

Energy Co. Limited

50%


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GENERATION OF 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 and cold 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 steamfrom 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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AUTOMATION : THE DEFINITION

The word automation is widely used today in relation to various types of applications,

such as office automation, plant or process automation.

This subsection presents the application of a control system for the automation of a

process / plant, such as a power station. In this last application, the automation

actively controls the plant during the three main phases of operation: plant start-up,

power generation in stable or put During plant start-up and shut-down, sequence

controllers as well as long range modulating controllers in or out of operation every

piece of the plant, at the correct time and in coordinated modes, taking into account

safety as well as overstressing limits.

During stable generation of power, the modulating portion of the automation system

keeps the actual generated power value within the limits of the desired load demand.

During major load changes, the automation system automatically redefines new set

points and switches ON or OFF process pieces, to automatically bring the individual

processes in an optimally coordinated way to the new desired load demand. This load

transfer is executed according to pre- programmed adaptively controlled load

gradients and in a safe way.


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AUTOMATION: THE BENEFITS

The main benefits of plant automation are to increase overall plant availability and

efficiency. The increase of these two factors is achieved through a series of features

summarized as follows:

1. Optimisation of house load consumption during plant start- up,shut-down and operation, via:

Faster plant start-up through elimination of control errors creating delays. Faster sequence of control actions compared to manual ones. Figures 1

shows the sequence of a rapid restart using automation for a typical coal-

fired station. Even a well- trained operator crew would probably not be

able to bring the plant to full load in the same time without considerable

risks.

Co-ordination of house load to the generated power output.

2. Ensure and maintain plant operation, even in case ofdisturbances in the control system, via:

Coordinated ON / OFF and modulating control switchover capability froma sub process to a redundant one.

Prevent sub-process and process tripping chain reaction following aprocess component trip.

3. Reduce plant / process shutdown time for repair andmaintenance as well as repair costs, via:

Protection of individual process components against overstress (in a stableor unstable plant operation).

Bringing processes in a safe stage of operation, where process componentsare protected against overstress


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CONTROL AND MONITORING MECHANISMS

There are basically two types of Problems faced in a Power Plant Metallurgical Mechanical

Mechanical Problemcan be related to Turbines that is the max speed permissible for a

turbine is 3000 rpm , so speed should be monitored and maintained at that level

Metallurgical Problem can be view as the max Inlet Temperature for Turbile is 1060

oC so temperature should be below the limit.

Monitoring of all the parameters is necessary for the safety of both:

Employees Machines

So the Parameters to be monitored are :

Speed Temperature Current Voltage Pressure Eccentricity Flow of Gases Vaccum Pressure Valves Level Vibration


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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 the electronic computation chipsets and recorders and lastly the

controlling circuitry, all fall under this.


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MANOMETRY LAB

TRANSMITTERS: It 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 and amplified. 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.

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.

BOURDEN PRESSURE GAUGE :Its an oval section tube. Its one end is fixed. It isprovided 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.

Pressure Measurement

The U-Tube or Manometer: Liquid contained in a tube bend in the form of a U will

respond to a difference in pressure across the two limbs. A glass tube of uniform

cross-sectional-area is bent to form a U and partly filed with a liquid of known density

'd' p.s.l.

Measurement of Atmospheric Pressure: Atmospheric pressure will support calcium

of Mercury approximately 30 inches in a U-tube provided a good vacuum is

maintained in one limb. Ifa U-tube is replaced with a straight limb about 35 inches

long, one end closed, then being filed with clean, dry mercury and then inverted in a

container of mercury open to the atmosphere, the mercury would fall in the tube

forming a good vacuum above it.


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Fig.2 Fortin.Barometer

Single Tube Manometer This is used for measuring low pressure and for testing and

recalibration low-pressure instruments of al types. If the ratio of the area of one tubeis considerably greater than other, then practically al the movement takes place in the

smal manometer tube and for al practical purposes only the one limb need be read.

Kenotometer The low pressures produced in steam condensers are usually measured

in inches of mercury, marking downwards from atmospheric pressure. A high

working vacuum of 29.5 inches of mercury is the same as an absolute pressure of 0.5

inch of mercury, or approximately 0.25 p.s.i (absolute). One device for measuring the

absolute pressure in a condenser is the Kenotometer.

Bourdon Pressure Gauge: This is the most commonly used of al pressure measuring

devices. (Range 10- 80,000 p.s.i). Here, a tube of oval section is bent into a circular

arc. One end is sealed and the other end fixed to a solid block into which the applied

pressure is fed. The tube will "uncurl" as the pressure (operating Force) increases, or

will 'Curl up' as the vacuum increases; so giving a movement of the free end which is

proportional to the change in pressure. The Controlling Force will depend upon the

thickness of the tube and the material from which it is made.


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Fig.3 Typical Arrangement of Bourden Gauge

SpecialTypes Of Pressure Gauges

Spiral Tube: This type is used for low-pressure indication and recording when a C-

shaped Bourden tube is not suitable and where power is required. By making the ovaltube in the form of a spiral an enlarged movement of the free end is achieved and thus

the tube becomes more sensitive over pressure ranges below 10 p.s.i.

Helical Tube: For higher pressures the tube is wound in the form of a helix and is

often used in pressure recorders. Range 0-80,000 p.s.i.

Critical Type: This is used in boiler houses to enable distant reading of the steam

pressure to be made to the nearest 1 p.s.i over a range of say 15 p.s.i. The movement

of a pressure sensitive element is transmitted to a pointer and scale via linkages,

which only allow the pointer to operate over a selected range of pressure to either side

of the normal steam pressure.


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Fig.4 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 tor local indication on closed or open

vessels.

"Float Operated Dial" are used for small tanks and congested areas. The float arm is

connected to a quadrant and pinion which rotates the pointer over a scale.

Pressure operated types Since the pressure acting on any area at the bottom of a tank

depends only upon the depth and density of the contained liquid, a measure of this

pressure is proportional to the liquid level.


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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, andwhere 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 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 filed with an inert gas under a slight pressure is exposed to

the pressure 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 of

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.

Fig.5 Air Purge Level Measurement


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PROTECTION AND INTERLOCK LAB

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 circuitsby 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 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 thesurges of the current that produces temperatures just near the melting point. c)

Silver fusible elements can be raised from normal operating temperature to

vaporization quicker than any other material because of its comparatively low

specific heat.

3. 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 occurs the contacts separate and are is stuck between them. There are

three types of - MANUAL TRIP - THERMAL TRIP - SHORT CIRCUIT TRIP


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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 but they 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.


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PYROMETERY LAB

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

Temperature Measurement

. The change may be observed with substance itself or in a subsidiary system in

thermodynamic equilibrium.

Fig.6 Rod Type Thermostat

Solid Rod Thermometers: A temperature sensing - Controlling device may be

designed incorporating in its construction the principle that some metals expand more

than others for the same temperature range.

Bi-Metalic Strip : These are composed of two metals, as the name implies, whose

coeficients of linear expansion are dissimilar. These two metal plates are welded

together as a sandwich. When heated, both metals expand, but the metal with greatest


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coeficient of linear expansion wil expand more causing the sandwich to curl up or

down depending on the position of this metal.

Fig.7 Helical Bi-Metallic Strip

Liquid in Glass Thermometers : The coeficient of cubical expansion of

mercury is about eight time greater that of glass. Therefore, a glass container holding

mercury, when heated, wil expand far less than the mercury it contains. At a high

temperature the mercury will occupy a greater fraction of the volume of the container

than it will at a low temperature.

Under normal atmospheric conditions mercury normally boils at a temperature of

(347C). To extend the range of a 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 filed 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 al 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 Tube : Most common and simplest type Spiral type : More sensitive and used where compactness is necessary Helical Type : Most sensitive and compact.Pointer may be mounted direct on

end of helix which rotates, thus eliminating backlash and lost motion.


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Fig.8 Liquid Expansion Thermometer with C Bourden

(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 isL shaped thermometer which is designed to reach all inaccessible places.

Fig.9 Bulb Forms

A. PLAIN BULB B. UNION BULB; C. POCKET BULB D. WALL MOUNTING

E. SHORT COtL. F. LONG COIL; G. FINNED STRAIGHT H.WATCH CAPSULE


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2) ULTRA VIOLET SENSOR : 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.

Fig.10 Thermocouple

(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).

Gas Thermometers : In Efect of Heat, the volume of a gas. at constant pressure,

wil change with relation to temperature change, and that at constant volume the

pressure changes in relation to temperature. Therefore, if a bulb, capillary and

bourdon tube enclose a certain volume of gas and the both of that assembly is

subjected to heat, or change of the same, the changes of pressure, effected by the heat,

within the system, can be directly related to temperature. The later will, of course be

shown though the movement of the free end of the bourdon tube.


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FURNACE SAFETY AND SUPERVISORY SYSTEM LAB

This 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 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.


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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.

ANNUNCIATION 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.


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ECOLOGICAL MONITORING PROGRAMME

NTPC has undertaken a comprehensive Ecological Monitoring Programme through

Satellite Imagery Studies covering an area of about 25 Kms radius around some of its

major plants. The studies have been conducted through National Remote Sensing

Agency (NRSA), Hyderabad at its power stations at Ramagundam, Farakka, Korba,

Vindhyachal, Rihand and Singrauli. These studies have revealed significant

environmental gains in the vicinity areas of the project as a result of pursuing sound

environment management practices. Some of these important gains which have been

noticed are increase in dense forest area, increase in agriculture area, increase in

average rainfall, decrease in waste land etc. In general, the studies, as such, have

revealed that there is no significant adverse impact on the ecology due to the project

activities in any of these stations. Such studies conducted from time to time around a

power project have established comprehensive environment status at various post

operational stages of the project.


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USE OF WASTE PRODUCTS & SERVICES -ASH UTILIZATION

Ash is the main solid waste which is put into use for various products and services.

NTPC has adopted user friendly policy guidelines on ash utilisation.

In order to motivate entrepreneurs to come forward with ash utilisation schemes,

NTPC offers several facilities and incentives. These include free issue of all types of

ash viz. Dry Fly Ash / Pond Ash / Bottom Ash and infrastructure facilities, wherever

feasible. Necessary help and assistance is also offered to facilitate procurement of

land, supply of electricity etc from Government Authorities. Necessary techno-

managerial assistance is given wherever considered necessary. Besides, NTPC uses

only ash based bricks and Fly Ash portland pozzolana cement (FAPPC) in most of its

construction activities. Demonstration projects are taken up in areas of Agriculture,

Building materials, Mine filling etc. The utilisation of ash and ash based products is

progressively increasing as a result of the concrete efforts of these groups.


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Environment Management, Occupational Health and

SafetySystems:

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.

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 mentioned below have been installed to control air and water

pollution.

Electrostatic Precipitators

Flue Gas Stacks

Neutralisation Pits

Low-NOX Burners

Coal Settling Pits / Oil Settling Pits

DE & DS System

Cooling Towers

Ash Dykes & Ash Disposal systems

Ash Water Recycling System

Dry Ash Extraction System (DAES)

Liquid Waste Treatment Plants & Management System

Sewage Treatment Plants & Facilities

Environmental Institutional Set-up

Environment Reviews

Up gradation & retrofitting of Pollution Control Systems

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