Download NTPC summer training report

1. 1 ABOUT NTPC India‟s largest power company, NTPC was set up in 1975 to
accelerate power development in India. NTPC is emerging as a diversified power major
with presence in the entire value chain of the power generation business. Apart from
power generation, which is the mainstay of the company, NTPC has already ventured
into consultancy, power trading, ash utilization and coal mining. NTPC ranked 341st in
the „2010, Forbes Global 2000‟ ranking of the World‟s biggest companies. NTPC
became a Maharatna company in May, 2010, one of the only four companies to be
awarded this status. The total installed capacity of the company is 39,174 MW (including
JVs) with 16 coal based and 7 gas based stations, located across the country. In addition
under JVs, 7 stations are coal based & another station uses naptha/LNG as fuel. The
company has set a target to have an installed power generating capacity of 1,28,000 MW
by the year 2032. The capacity will have a diversified fuel mix comprising 56% coal,
16% Gas, 11% Nuclear and 17% Renewable Energy Sources(RES) including hydro. By
2032, non-fossil fuel based generation capacity shall make up nearly 28% of NTPC‟s
portfolio. NTPC has been operating its plants at high efficiency levels. Although the
company has 17.75% of the total national capacity, it contributes 27.40% of total power
generation due to its focus on high efficiency.
2. 2 In October 2004, NTPC launched its Initial Public Offering (IPO) consisting of
5.25% as fresh issue and 5.25% as offer for sale by Government of India. NTPC thus
became a listed company in November 2004 with the Government holding 89.5% of the
equity share capital. In February 2010, the Shareholding of Government of India was
reduced from 89.5% to 84.5% through Further Public Offer. The rest is held by
Institutional Investors and the Public.
3. 3 Strategies of NTPC Techno
-A new initiative for development
of technologies with focus on fundame
Mechanism to help get / earn µCertified Emission Reduction.
zen NTPC has
re of
project affected persons and the local population around NTPC projects are taken care of
Thecompanyhasalsotakenupdistributedgenerationforremoteruralareas Partnering
government in various
al Electrification work under Rajiv Gandhi Garmin
Centre for Power Efficiency &
second largest owner of trees in the country after the Forest department
5. 5 Vision “To be the world‟s largest and best power producer, powering India‟s
growth.” Mission “Develop and provide reliable power, related products and services at
competitive prices, integrating multiple energy sources with innovative and eco-friendly
technologies and contribute to society.” Core Values – BE COMMITTED B Business
Ethics E Environmentally & Economically Sustainable C Customer Focus O
Organizational & Professional Pride M Mutual Respect & Trust M Motivating Self &
others I Innovation & Speed T Total Quality for Excellence T Transparent & Respected
Organization E Enterprising D Devoted
6. 6 JOURNEY OF NTPC
7. 7 NTPC Environment Policy NTPC is committed to the environment, generating
power at minimal environmental cost and preserving the ecology in the vicinity of the
plants. NTPC has undertaken massive a forestation in the vicinity of its plants.
Plantations have increased forest area and reduced barren land. The massive a forestation
by NTPC in and around its Ramagundam Power station (2600 MW) have contributed
reducing the temperature in the areas by about 3°c. NTPC has also taken proactive steps
for ash utilization. In 1991, it set up Ash Utilization Division A "Centre for Power
Efficiency and Environment Protection- CENPEE" 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 its Rehabilitation and Resettlement programmes, the company
endeavors to improve the overall socio economic status Project Affected Persons. NTPC
was among the first Public Sector Enterprises to enter into a Memorandum of
Understanding-MOU with the Government in 1987-88. NTPC has been placed under the
'Excellent category' (the best category) every year since the MOU system became
operative. Harmony between man and environment is the essence of healthy life and
growth. Therefore, maintenance of ecological balance and a pristine environment has
been of utmost importance to NTPC. It has been taking various measures discussed
below for mitigation of environment pollution due to power generation.
NTPCisthesecondlargestowneroftreesinthecountryaftertheForestdepartment.
8. 8 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 is 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 complies 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.
9. 9 Flue Gas Stacks: Tall Flue Gas Stacks have been provided for wide dispersion of the
gaseous emissions (SOX, NOX etc.) into the atmosphere. Low-NOX Burners: In gas
based NTPC power stations, NOX emissions are controlled by provision of Low- NOX
Burners (Dry or wet type) and in coal fired stations, by adopting best combustion
practices. Neutralization Pits: Neutralization pits have been provided in the Water
Treatment Plant (WTP) for pH correction of the Effluents before discharge into Effluent
Treatment Plant (ETP) for further treatment and use. Coal Settling Pits / Oil Settling Pits:
In these Pits, coal dust and oil are removed from the effluents emanating from the Coal
Handling Plant (CHP), coal yard and Fuel Oil Handling areas before discharge into ETP.
DE & DS Systems: Dust Extraction (DE) and Dust Suppression (DS) systems have been
installed in all coal fired power stations in NTPC to contain and extract the fugitive dust
released in the Coal Handling Plant (CHP). Cooling Towers: Cooling Towers have been
provided for cooling the hot Condenser cooling water in closed cycle, Condenser Cooling
Water (CCW) Systems. This helps in reduction in thermal pollution and conservation of
fresh water.
10. 10 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 arrangement for
changeover of the ash slurry feed points for even filling of the pond and for effective
settlement of the ash particles. Ash in slurry form is discharged into the lagoons where
ash particles get settled from the slurry and clear effluent water is discharged from the
ash pond. The discharged effluents conform to standards specified by CPCB and the
same is regularly monitored. At its Dadri Power Station, NTPC has set up a unique
system for dry ash collection and disposal facility with Ash Mound formation. This has
been envisaged for the first time in Asia which has resulted in progressive development
of green belt besides far less requirement of land and less water requirement as compared
to the wet ash disposal system. Ash Water Recycling System: Further, in a number of
NTPC stations, as a proactive measure, Ash Water Recycling System (AWRS) has been
provided. In the AWRS, the effluent from ash pond is circulated back to the station for
further ash sluicing to the ash pond. This helps in savings of fresh water requirements for
transportation of ash from the plant. The ash water recycling system has already been
installed and is in operation at Ramagundam, Simhadri, Rihand, Talcher Kaniha, Talcher
Thermal, Kahalgaon, Korba and Vindhyachal. The scheme has helped stations to save
huge quantity of fresh water required as make-up water for disposal of ash. Dry Ash
Extraction System (DAES): Dry ash has much higher utilization potential in ash-based
products (such as bricks, aerated autoclaved concrete blocks, concrete, Portland
pozzolana cement, etc.). DAES has been installed at Unchahar, Dadri, Simhadri,
Ramagundam, Singrauli, Kahalgaon, Farakka, Talcher Thermal, Korba, Vindhyachal,
Talcher Kaniha and BTPS.
11. 11 Liquid Waste Treatment Plants & Management System: The objective of
industrial liquid effluent treatment plant (ETP) is to discharge lesser and cleaner effluent
from the power plants to meet environmental regulations. After primary treatment at the
source of their generation, the effluents are sent to the ETP for further treatment. The
composite liquid effluent treatment plant has been designed to treat all liquid effluents
which originate within the power station e.g. Water Treatment Plant (WTP), Condensate
Polishing Unit (CPU) effluent, Coal Handling Plant (CHP) effluent, floor washings,
service water drains etc. The scheme involves collection of various effluents and their
appropriate treatment centrally and re-circulation of the treated effluent for various plant
uses. NTPC has implemented such systems in a number of its power stations such as
Ramagundam, Simhadri, Kayamkulam, Singrauli, Rihand, Vindhyachal, Korba, Jhanor
Gandhar, Faridabad, Farakka, Kahalgaon and Talcher Kaniha. These plants have helped
to control quality and quantity of the effluents discharged from the stations. Sewage
Treatment Plants & Facilities: Sewage Treatment Plants (STPs) sewage treatment
facilities have been provided at all NTPC stations to take care of Sewage Effluent from
Plant and township areas. In a number of NTPC projects modern type STPs with
Clarifloculators, Mechanical Agitators, sludge drying beds, Gas Collection Chambers etc.
have been provided to improve the effluent quality. The effluent quality is monitored
regularly and treated effluent conforming to the prescribed limit is discharged from the
station. At several stations treated effluents of STPs are being used for horticulture
purpose.
12. 12 ABOUT BTPS BADARPUR THERMAL POWER STATION was established on
1973 and it was the part of Central Government. On 01/04/1978 is was given as No Loss
No Profit Plant of NTPC. Since then operating performance of NTPC has been
considerably above the national average. The availability factor for coal stations has
increased from 85.03 % in 1997-98 to 90.09 % in 2006-07, which compares favorably
with international standards. The PLF has increased from 75.2% in1997-98 to 89.4%
during the year 2006-07 which is the highest since the inception of NTPC. Badarpur
thermal power station started with a single 95 mw unit. There were2moreunits
(95MWeach) installedinnext2
consecutiveyears.Nowithastotalfiveunitswithtotalcapacityof 720MW.OwnershipofBTPS
wastransferredtoNTPC witheffect from 01.06.2006 through GOIs Gazette Notification .
The power is supplied to a 220 KV network that is a part of the northern grid. The ten
circuits through which the power is evacuated from the plant are: 1. Mehrauli 2. Okhla 3.
Ballabgarh 4. Indraprastha 5. UP (Noida) 6. Jaipur
13. 13 Given below are the details of unit with the year they’re installed.
14. 14 StationLocation Badarpurissituatedonly20kmaway
fromDelhi.TheplantislocatedontheleftsideoftheNational Highway(DelhiMathuraRoad)anditcomprisesof430hectares(678acres) borderedby the Agra Canal from
East and by Mathura-Delhi Road from West. However, the area for ash
disposalisdoneintheDelhiMunicipallimitandismaintained
withthehelpofDelhiDevelopment
Authority.Theplantisalsoclosetotheprojectof220kvDoubleCircuitTransmissionlinebetwee
nthe I.P.stationandBallabgarhCoolingWaterisobtainedfromAgraCanal for the cooling
system. Additional 60 cusecs channel has also been constructed parallel to the Agra
Canal so as to obtain uninterrupted water supply during the slit removing operation in
AgraCanal.
15. 15 OPERATION OF A POWER PLANT Basic Principle As per FARADAY‟s Law“Whenever the amount of magnetic flux linked with a circuit changes, an EMF is
produced in the circuit. Generator works on the principle of producing electricity. To
change the flux in the generator turbine is moved in a great speed with steam.” To
produce steam, water is heated in the boilers by burning the coal. In a Badarpur Thermal
PowerStation, steam is produced and used to spin a turbine that operates a generator.
Water is heated, turns into steam and spins a steam turbine which drives an electrical
generator. After it passes through the turbine, the steam is condensed in a condenser; this
is known as a Rankine cycle. The electricity generated at the plant is sent to consumers
through high-voltage power lines The Badarpur Thermal Power Plant has Steam TurbineDriven Generators which has a collective capacity of 705MW. The fuel being used is
Coal which is supplied from the Jharia Coal Field in Jharkhand. Water supply is given
from the Agra Canal.
16. 16 Basic Steps of Electricity Generation
Thebasicstepsinthegenerationofelectricityfromcoalinvolvesfollowingsteps:
17. 17 Coal to Electricity : Basics
18. 18
19. 19
20. 20 PARTS OF A POWER PLANT The various parts are listed below:- 1. Cooling
tower 2. Cooling water pump 3. Transmission line (3-phase) 4. Unit transformer (3phase) 5. Electric generator (3-phase) 6. Low pressure turbine 7. Condensate extraction
pump 8. Condenser 9. Intermediate pressure turbine 10. Steam governor valve 11. High
pressure turbine
21. 21 12. Deaerator 13. Feed heater 14. Coal conveyor 15. Coal hopper 16. Pulverised
fuel mill 17. Boiler drum 18. Ash hopper 19. Super heater 20. Forced draught fan 21.
Reheater 22. Air intake 23. Economiser 24. Air preheater 25. Precipitator 26. Induced
draught fan 27. Flue Gas 1. Cooling Tower Cooling towers are heat removal devices used
to transfer process waste heat to the atmosphere. Cooling towers may either use the
evaporation of water to remove process heat and cool the working fluid to near the wetbulb air temperature or in the case of closed circuit dry cooling towers rely solely on air
to cool the working fluid to near the dry-bulb air temperature. Common applications
include cooling the circulating water used in oil refineries, chemical plants, power
stations and building cooling. The towers 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 structures 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 absorbed
heat is rejected to the atmosphere by the evaporation of some of the cooling water in
mechanical forced-draft or induced
22. 22 Draft towers or in natural draft hyperbolic shaped cooling towers as seen at most
nuclear power plants. 2. Cooling Water Pump it pumps the water from the cooling tower
which goes to the condenser. 3. 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
conductive material to transmit electric power than equivalent single phase, two phase, or
direct current system at the same voltage. In a three phase system, three circuits reach
their instantaneous peak values at different times. Taking current in one conductor as the
reference, the currents in the other two are delayed in time by one-third and two-third of
one cycle .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 of one cycle. Generators output at a
voltage that ranges from hundreds of volts to 30,000 volts. 4. Unit transformer (3-phase)
At the power station, transformers step-up this voltage to one more suitable for
transmission. After numerous further conversions in the transmission and distribution
network the power is finally transformed to the standard mains voltage (i.e. the
“household” voltage). The power may already have been split into single phase at this
point or it may still be three phase. Where the step-down is 3 phase, the output of this
transformer is usually star connected with the standard mains voltage being the phase23. 23 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 (
or wild leg) and neutral and 240 V between any two phase) to be available from the same
supply. 5. 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 maybe water falling through the turbine or steam
turning a turbine (as is the case with thermal power plants). There are several
classifications for modern steam turbines. Steam turbines are used in our entire major
coal fired power stations to drive the generators or alternators, which produce electricity.
The turbines themselves are driven by steam generated in "boilers “or "steam generators"
as they are sometimes called. Electrical power stations use large steam turbines driving
electric generators to produce most (about 86%) of the world‟s electricity. These
centralized stations are of two types: fossil fuel power plants and nuclear power plants.
The turbines used for electric power generation are most often directly coupled to theirgenerators .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. 6.
Low Pressure Turbine Energy in the steam after it leaves the boiler is converted into
rotational energy as it passes through the turbine. The turbine normally consists of several
stages 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 and direct
the flow onto the
24. 24 rotating blades. The rotating blades convert the kinetic energy into impulse and
reaction 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. Low
Pressure Turbine (LPT) consists of 4x2 stages. After passing through Intermediate
Pressure Turbine steam is passed through LPT which is made up of two parts- LPC
REAR & LPC FRONT. As water gets cooler here it gathers into a HOTWELL placed in
lower parts of turbine. 7. Condensation Extraction 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 returning 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
water into the boiler, the pump must generate sufficient pressure to overcome the steam
pressure developed by the boiler. This is usually accomplished through the use of a
centrifugal pump. Feed water pumps usually run intermittently and are controlled by a
float switch or other similar level-sensing device energizing the pump when it detects a
lowered liquid level in the boiler. Some pumps contain a two-stage switch. As liquid
lowers to the trigger point of the first stage, the pump is activated. If 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.
25. 25 8. Condenser The steam coming out from the Low Pressure Turbine (a little above
its boiling pump) is brought into thermal contact with cold water (pumped in from the
cooling tower) in the condenser, where it condenses rapidly back into water, creating near
Vacuum-like conditions inside the condenser chest. 9. Intermediate Pressure Turbine
Intermediate Pressure Turbine (IPT) consists of 11 stages. When the steam has been
passed through HPT it enters into IPT. IPT has two ends named as FRONT & REAR.
Steam enters through front end and leaves from Rear end. 10. Steam Governor Valve
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. Control valves
are valves used within industrial plants and elsewhere to control operating conditions
such as temperature, pressure, flow and liquid level by fully or partially opening or
closing in response to signals received from controllers that compares a “set point” to a
26. 26 “process variable” whose value is provided by sensors that monitor changes in
such conditions. The opening or closing of control valves is done by means of electrical,
hydraulic or pneumatic systems. 11.High Pressure Turbine Steam coming from Boiler
directly feeds into HPT at a temperature of 540°C and at a pressure of 136 kg/cm2. Here
it passes through 12 different stages due to which its temperature goes down to 329°C
and pressure as 27 kg/cm2. This line is also called as CRH – COLD REHEAT LINE. It is
now passed to a REHEATER where its temperature rises to 540°C and called as HRHHOT REHEATED LINE. 12. Deaerator A Deaerator 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 the metal. The solids will deposit on the heating surfaces
giving rise to localized heating and tube ruptures due to overheating. Under some
conditions it may give rise 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) 13. 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 irreversibility involved in steam generation and therefore improves the
thermodynamic efficiency of the system. This reduces plant operating costs and also
helps to avoid thermal shock to the boiler
27. 27 metal when the feed water is introduced back into the steam cycle. In a steam
power (usually modelled as a modified Rankine cycle), feed water heaters allow the feed
water to be brought up to the saturation temperature very gradually. This minimizes the
inevitable irreversibility associated with heat transfer to the working fluid (water). 14.
Coal conveyor Coal conveyors are belts which are used to transfer coal from its storage
place to Coal Hopper. A belt conveyor consists of two pulleys, with a continuous loop of
material- the conveyor Belt – that rotates about them. The pulleys are powered, moving
the belt and the material on the belt forward. Conveyor belts are extensively used to
transport industrial and agricultural material, such as grain, coal, ores etc. 15. Coal
Hopper Coal Hoppers are the places which are used to feed coal to Fuel Mill. It also has
the arrangement of entering Hot Air at 200°C inside it which solves our two purposes:- 1.
If our Coal has moisture content then it dries it so that a proper combustion takes place. 2.
It raises the temperature of coal so that its temperature is more near to its Ignite
Temperature so that combustion is easy. 16. Pulverized Fuel Mill A pulveriser is a device
for grinding coal for combustion in a furnace in a fossil fuel power plant. 17. Boiler drum
Steam Drums are a regular feature of water tube boilers. It is reservoir of water/steam at
the top end of the water tubes in the water-tube boiler. They store the steam generated in
the water tubes and act as a phase separator for the steam/water mixture. The difference
in densities between hot and cold water helps in the accumulation of the “hotter”water/and saturated –steam into steam drum. Made from high-grade steel (probably
28. 28 stainless) and its working involve temperature of 390°C and pressure well above
350psi (2.4MPa). The separated steam is drawn out from the top section of the drum.
Saturated steam is drawn off the top of the drum. The steam will re-enter the furnace in
through a super heater, while the saturated water at the bottom of steam drum flows down
to the mud-drum /feed water drum by down comer tubes accessories include a safety
valve, water level indicator and fuse plug. 18. Ash Hopper 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 accumulate at the
bottom. 19. 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. 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 also stationary steam
engines including power stations. 20. Force Draught Fan External fans are provided to
give sufficient air for combustion. The forced draught fan takes air from the atmosphere
and, warms it in the air preheater for better combustion, injects it via the air nozzles on
the furnace wall. 21. Reheater Reheater is a heater which is used to raise the temperature
of steam which has fallen from the intermediate pressure turbine.
29. 29 22. Air Intake Air is taken from the environment by an air intake tower which is
fed to the fuel. 23. 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, heating, ventilating and air-conditioning. In boilers, economizer are heat
exchange devices that heat fluids , usually water, up to but not normally beyond the
boiling point of the fluid. Economizers are so named because they can make use of the
enthalpy and improving the boiler‟s efficiency. They are devices fitted to a boiler which
save energy by using the exhaust gases from the boiler to preheat the cold water used to
fill it (the feed water). Modern day boilers, such as those in cold fired power stations, are
still fitted with economizer which is decedents of Green‟s original design. In this context
there are turbines before it is pumped to the boilers. A common application of
economizer in steam power plants is to capture the waste heat 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. 24. Air Preheater Air preheater is a general term to describe any device
designed to heat air before another process (for example, combustion in a boiler). The
purpose of the air preheater is to recover the heat from the boiler flue gas which increases
the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas. As a
consequence, the flue gases are also sent to the flue gas stack (or chimney) at a lower
temperature allowing simplified design of the ducting and the flue gas stack. It also
allows control over the temperature of gases leaving the stack.
30. 30 25. 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 collection from black liquor boilers in pump mills, and catalyst collection from
fluidized bed catalytic crackers from several hundred thousand ACFM in the largest coalfired boiler applications. The original parallel plate-Weighted wire design (described
above) has evolved as more efficient (and robust) discharge electrode designs, today
focus is on rigid discharge electrodes to which many sharpened spikes are attached ,
maximizing corona production. Transformer –rectifier systems apply voltages of 50-100
Kilovolts at relatively high current densities. Modern controls minimize sparking and
prevent arcing, avoiding damage to the components. Automatic rapping systems and
hopper evacuation systems remove the collected particulate matter while on line allowing
ESPs to stay in operation for years at a time. 26. Induced Draught Fan The induced draft
fan assists the FD fan by drawing out combustible gases from the furnace, maintaining a
slightly negative pressure in the furnace to avoid backfiring through any opening. At the
furnace outlet and before the furnace gases are handled by the ID fan, fine dust carried by
the outlet gases is removed to avoid atmospheric pollution. This is an environmental
limitation prescribed by law, which additionally minimizes erosion of the ID fan. 27. Flue
gas stack A Flue gas stack is a type of chimney, a vertical pipe, channel or similar
structure through which combustion product gases called flue gases are exhausted to the
outside air. Flue gases are produced when coal, oil, natural gas, wood or any other large
combustion
31. 31 device. Flue gas is usually composed of carbon dioxide (CO2) and water vapour 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 sulphur 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 area
and thereby reduce the concentration of the pollutants to the levels required by
government's environmental policies and regulations. The flue gases are exhausted from
stoves, ovens, fireplaces or other small sources within residential abodes, restaurants,
hotels through other stacks which are referred to as chimneys.
32. 32 VARIOUS CYCLES AT POWER STATION
CYCLE
33. 33 PRIMARY AIR CYCLE P A FAN COLD AIR DUCT SEAL AIR FAN APH
HOT AIR DUCT PULVERISER
34. 34 SECONDARY AIR CYCLE W I N D B O X IGNITER FAN SCANNER AIR
FAN SCANNER COOLING FD FAN SCAPH APH WIND BOX BOILER
35. 35 ELECTRICITY CYCLE GENERATOR UAT UAT MAIN TRANSFORMER
SWITCH YARD OUTGOING FEEDER To Auxiliaries To Auxiliaries
36. 36 CONDENSATE CYCLE HOT WELL CONDENSATE PUMPS MAIN
EJECTOR GLAND STEAM COOLER WITH EJECTOR LP HEATER 2 LP HEATER
3 LP HEATER 4 DEAERATOR BOILER FEED PUMP
37. 37 FEED WATER CYCLE BOILER FEED PUMP HP HEATOR 5 HP HEATOR 6
HP HEATOR 7 FEED REGULATING STN ECONOMISER BOILER DRUM DOWN
COMERS UPRISERS BOILER DRUM
38. 38 STEAM CYCLE BOILER DRUM L.T.S.H. FLATEN S.H. FINAL S.H. H P
TURBINE C.R.H. H.R.H I P TURBINE L P TURBINE CONDENSER
39. 39 Coal Cycle
40. 40 Flue Gas Cycle
41. 41 ELECTRICAL MAINTENANCE DEPARTMENT – I (EMD-I) Electrical
maintenance division 1
June to29th June.
42. 42 MOTORS Motorscanbeclassifiedas ACandDC . ACMOTORS 1.
Squirrelcagemotor 2. Woundmotor 3. Slipringinductionmotor In modern thermal power
plant three phase squirrel cage induction motors are used but sometimedouble
woundmotor isusedwhenweneedhighstartingtorquee.g.inballmill.
THREEPHASEINDUCTIONMOTOR Ns(speed)=120f/p Stator canhandleconcentrated
singlelayer winding, witheachcoiloccupyingonestator slot
Themostcommontypeofwindingare: 1. DISTRIBUTEDWINDING: This type of winding
is distributed over a number of slots. 2. DOUBLELAYERWINDING: Eachstator
slotcontainssidesoftwodifferentcoils. SQUIRRELCAGEINDUCTIONMOTOR Squirrel
cage and wound cage have same mode of operation. Rotor conductors cut the rotating
stator magnetic field. an emf is induced across the rotor winding, current flows, a rotor
magnetic field is produced which interacts with the stator field causing a turning
43. 43 motion. The rotor does not rotate at synchronous speed, its speed varies with
applied load. The slip speed beingjustenoughtoenablesufficientinducedrotor
currenttoproducethepower dissipatedby the motor load and motor losses. BEARINGS
ANDLUBRICATIONS Agoodbearingisneededfor troublefreeoperationof
motor.Sinceitisverycostlypartofthe motor, due care has to be taken by checking it at
regular intervals. So lubricating plays an important role. Two types of lubricating are
widely used 1. Oil lubrication 2. Grease lubrication 3. Insulation INSULATION
Windingisanessentialpartsoitshouldbeinsulated.Followingtypesofinsulationarewidelyused
TYPESOFINSULATION CLASS TEMP UPTO WHICH THEY ARE EFFECTIVE
(DEGREE CENTIGRADE) Y 90 A 105 E 120 B 130 F 1
Fclassinsulationisgenerallypreferred.
44. 44 MAIN MOTOR USED INBOILERAND OFFSIDE AREA 1. IDFAN(2PER
UNIT) ItislocatedbetweenEPandchimneyusedfor creatinginduceddraftinthefurnace. 2.
PAFAN(2 PER UNIT) It is used for handling atmospheric air up to temperature 50
degree centigrade 3. FDFAN(2 PER UNIT) Itisusedfor handlingsecondaryair for
theboiler. 4. SCANNER FAN(2 PER UNIT) Itisrequiredforrequisiteair for scanner
cooling. 5. IGNITORFAN Itsuppliesair for coolingofigniters. INSTRUMENTSSEEN 1.
MICROMETER Thisinstrumentisusedfor measuringinsideaswellasoutsidediameter
ofbearing. 2. MEGGAR Thisinstrumentisusedfor measuringinsulationresistance. 3.
VIBRATIONTESTER
Itmeasuresthevibrationofthemotor.Itismeasuredinthreedimensions-axial,verticaland
horizontal.
45. 45 SWITCHGEAR INTRODUCTION Switchgear isonethatmakesor
breakstheelectricalcircuit.Itisa switchingdevicethatopens& closes a circuit that defined as
apparatus used for switching, Lon rolling & protecting the electrical
circuit&equipments.Theswitchgear
equipmentisessentiallyconcernedwithswitching&interrupting currentseither under
normalorabnormaloperatingconditions.Thetubular switch with ordinary fuse is simplest
form of switchgear & is used to control & protect&other equipmentsin
homes,officesetc.For circuitsofhigherratings,aHighRupturingCapacity (H.R.C) fuse in
condition with a switch may serve the purpose of controlling
&protectingthecircuit.However
suchswitchgearcannotbeusedprofitablyonhighvoltagesystem(3.3 KV)
for2reasons.Firstly,whena fuseblows,ittakessometimetoreplaceit&consequently there is
interruption of service to customer. Secondly, the fuse cannot successfully interrupt large
currents that result from the High Voltage System. In order to interrupt heavy fault
currents, automatic circuit breakers are used. There are very
fewtypesofcircuitbreakersinB.P.T.StheyareVCB,OCB,and
SF6gascircuitbreaker.Themostexpensive circuit breaker is the SF6 type due to gas. There
are various companies which manufacturethesecircuitbreakers: VOLTAS,JYOTI,and
KIRLOSKAR.Switchgearincludesswitches,fuses,circuitbreakers,relays&other
equipments
46. 46 THEEQUIPMENTSTHATNORMALLYFALLINTHISCATEGORYARE:- 1.
ISOLATOR Anisolator
isonethatcanbreaktheelectricalcircuitwhenthecircuitistobeswitchedonnoload. These are
used in various circuits for isolating the certain portion when required for
maintenanceetc.Anoperatingmechanismboxnormallyinstalledatgroundleveldrivestheisolat
or. Theboxhasanoperatingmechanisminadditiontoitscontactor
circuitandauxiliarycontactsmaybe solenoidoperatedpneumaticthreephasemotoror DC
motor transmittingthrough a spur gear to the torsion shaft of the isolator. Certain
interlocks are also provided with theisolator Theseare 1. Isolator
cannotoperateunlessbreaker isopen 2. Bus 1 and bus 2 isolators cannot be closed
simultaneously 3. Theinterlockcanbebypassintheeventofclosingofbuscoupler breaker. 4.
Noisolator canoperatewhenthecorrespondingearthswitchison 2. SWITCHINGISOLATOR
Switching isolator is capable of: 1. Interruptingchargingcurrent 2. Interrupting
transformer magnetizing current 3. Load transformer switching. Its main application is in
connection with the transformer feeder as the unit makes it possible to
switchgearonetransformer whiletheotherisstillonload. 3. CIRCUITBREAKER One
whichcanmakeor breakthecircuitonloadandevenonfaultsisreferredtoascircuit
breakers.Thisequipmentisthemostimportantandisheavydutyequipmentmainlyutilized for
protection of various circuits and operations on load. Normallycircuitbreakers
installedareaccompaniedbyisolators.
47. 47 4. LOADBREAK SWITCHES Thesearethoseinterruptingdeviceswhichcanmakeor
break circuits.Thesearenormallyon same circuit,whicharebackedbycircuitbreakers 5.
EARTH SWITCHES Devices which are used normally to earth a particular system, to
avoid any accident happening
duetoinductiononaccountofliveadjoiningcircuits.Theseequipmentsdonothandle
anyappreciable current at all. Apart from this equipment there are a number of relays etc.
interlocking. It is classified in following ways:- 1. MAINSWITCH Main switch is control
equipment which controls or disconnects the main supply. The main switch for 3 phase
supply is available for the range 32A, 63A, 100A, 200Q, 300A at 500V grade. 2. FUSES
With Avery high generating capacity of the modern power stations extremely heavy
carnets would flow in the fault and the fuse clearing the fault would be required to
withstand extremely heavy stress in process. It is used for supplying power to auxiliaries
with backup fuse protection. 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. CONTACTORS AC Contractors are 3 poles suitable for D.O.L Starting of
motors and protecting the connected motors.
48. 48 4. OVERLOAD RELAY For overload protection, thermal overload relay are best
suited for this purpose. They operate due to the action of heat generated by passage of
current through relay element. 5. AIRCIRCUIT BREAKERS It is seen that use of oil in
circuit breaker may cause a fire. So in all circuits breakers at large capacity air at high
pressure is used which is maximum at the time of quick tripping of contacts. This reduces
the possibility of sparking. The pressure may vary from 50-60kg/cm^2 for high and
medium capacity circuit breakers.
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
-HKH 12/1000
-220 V/DC
50. 50 2. AIRCIRCUIT BREAKER In this the compressed air pressure around 15 kg per
cm^2 is used for extinction of arc caused by flow of air around the moving circuit . The
breaker is closed by applying pressure at lower opening and opened by applying pressure
at upper opening. When contacts operate, the cold air rushes around the movable contacts
and blown the arc: It has the following advantages over OCB:- i. Fire hazard due to oil
are eliminated. ii. Operation takes place quickly. iii. There 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 KV Current-630 A Auxiliary
current-220 V/DC
51. 51 3. SF6CIRCUITBREAKER This type of circuit breaker is of construction to dead
tank bulk oil to circuit breaker but the principle of current interruption is similar to that of
air blast circuit breaker. It simply employs the arc extinguishing medium namely SF6.
When it is broken down under an electrical stress, it will quickly reconstitute itself.
Circuit Breakers-1600
-110 KA
52. 52 4. VACUUMCIRCUITBREAKER It works on the principle that vacuum is used
to save the purpose of insulation and. In regards of insulation and strength, vacuum is
superior dielectric medium and is better that all other medium except air and sulphur
ated making
Current-220 V/DC
53. 53 COALHANDLINGPLANT(CHP) The coal handling plant consists of two plants:
supplies coal to Unit- I, II, III & NCHP supplies coal to Unit- IV and V.
COALSUPPLIEDATBTPS Coal is supplied to BTPS by Jharia coal mines. It is noncooking coal and has following specifications:matter- 35% lorific Valuereceived in railway box racks containing 20 one wagon tippler in NCHP, in total 3, capacity 80 toneach.
54. 54 COAL CYCLE
55. 55 OLD COAL HANDLING PLANT (OCHP) KEY DIAGRAM
56. 56 The main constituents of OCHP plant are:- WAGONTIPPLER Wagon from coal
yard come to the tippler and emptied here. There are 2 wagon tipplers in the OCHP. The
tippler is tilted to about 137°- 141° so that coal from the wagon is emptied into the
hopper. Elliptics feeder is used in OCHP. Total 8 feeders are used, 4 in each hopper. Slip
Ring Induction Motor is used to operate a wagon tippler. This type of IM is used in the
tippler because of its high resistance, low speed & high torque characteristics. The rating
of the motor used is: o Power 55 Kw o Voltage 415V o Current 102A o Speed 1480rpm o
Phase 3 o Frequency 50Hz Three types of wagon tipplers are used:- a) ROTASIDE: - It is
used for open type wagons in which each wagon carries around 50- 56 tons of coal. The
wagon is tilted by 150° to put the coal in the unloading hopper. b) ROTARY: - In this
case the unloading hopper is placed directly under the tippler table. This is also used to
tilt the wagon tippler to 180°. c) ROCKING TYPE: - It is used for close type wagons. In
this hoppers is placed by the side of end rocking is provided to facilitate unloading of
coal at corners of the wagon.
57. 57 CONVEYER Conveyer belts are used in the OCHP to transfer coal from one place
to other as required in a convenient&safe way.Allthebeltsarenumberedaccordingly
sothattheir functioncanbeeasily demarcated. These belts are made of rubber & move with
a speed of 250-300 m/min. Motor employedfortheconveyer hasa
capacityof150HP.Theseconveyershavea capacityof carrying the coal at the rate of 400
ton/hr. ZEROSPEED SWITCH It is used as a safety device for the motor i.e. if the belt is
not moving & the motor is ON, then
itburnstosavethemotor.Thisswitchchecksthespeedofthebelt&switchesoffthemotor when
speediszero. METALDETECTOR As the conveyer belt take coal from wagon to crusher
house, no metal piece should go along with coal. To achieve this objective, metal
detectors & separators are used. In the OCHP, these MD‟s are installed in the conveyer
belts 2A & 2B. CRUSHERHOUSE Both the plants i.e. OCHP & NCHP use TATA
crusher powered by BHEL motor. Crusher is of ring typeandthemotorisaHT motor
ofrating400HP&6.6 KV.Crusherisdesignedto crushthepieces to 20 mm size i.e.
practically considered as the optimum size for transfer via conveyer.
ROTARYBREAKER
Ifanylargepieceofmetalofanyhardsubstanceslikemetalimpuritiescomesintheconveyer
beltwhich
causeloadonthemetalseparator,thentherotarybreakerrejectsthemreducingtheloadonthemeta
l detector.
58. 58 STACKER-CUM-RECLAIMER It is used for stacking & reclaiming the coal
from the stockyard in case of unavailability of wagons from coal mines.
PLOUGHFEEDER Theseplough feedersaregenerallyinstalledunder slotbunkersor
hoppers.Theseareusedtop lough the coal to the belt from the coal fed from stockyard.
These feeders used in this power station are generally of rotary type. TRIPPERS
Trippersareprovidedintheconveyer tocollectthematerialatdesiredlocationoneither
sideoralongthe conveyer withthehelpofchute/ductsfittedwithtripper itself.Themotor
inthetrippercanmakeit move bothinforwardandreversedirection. PULL GUARDSWITCH
Thesearetheswitcheswhichareinstalledatevery10mgapina conveyer belttoensurethesafety
of motors running the conveyer belts. If at any time some accident happens or coal jumps
from belt and starts collecting at a place, this switch can be moved to NO(normally open)
position from NC (normally closed) position to stop conveyor belt from moving. At this
timetheproblemcanbecorrected&thenagaintheswitchcanbemovedtoNC(normallyclosed)
position for normal working again. INTERLOCKS: - The CHP is normally spread over a
wide area with centralized control room. Elaborate scheme is
thereforeprovided.Ifduetoanyemergencyeither theconveyor beltorthemotor hastobe
stopped, due to this interlocking all the other motors connected to it will automatically
stop &will not work till signal is given from the control room.
59. 59 The control & protection scheme normally includes: system to warn
that the plant is going to be started. The plant can be started only after a definite time
Tripping of conveyor from
speed switch for protection against belt slippage.
SEQUENTIALOPERATIONOFOCHP:- I. Unloadingthecoal II. Crushing & storage. III.
Conveyingtoboiler bunkers. a) Coal arrives to plant via road, rail, sea, and river or canal
route from collieries. Most of it
arrivesbyrailrouteonlyinrailwaywagons.Coalrequirementbythisplantis approximately
10,500 metric ton/day. b) This coal is tippled into hoppers. If the coal is oversized (400
mm sq), then it is broken manuallysothatitpassesthehopper meshwherethroughelliptic
feeder itisputinto vibrators&thentoconveyor belt1A &1B. c) The coal through conveyor
belts 1A & 1B goes to the crusher house. Also the extra coal is sent to stockyard through
these belts. d) Inthecrusher housethe smallsizecoalpiecesgoesdirectlytothebelt2A &2B
whereasthe bigsizecoalpiecesarecrushedinthecrusher &thengiventothebelts2A&2B. e)
Thecrushedcoalistakentothebunker housevia theconveyor belts3A&3B whereitcanbe
usedfor further operations.
60. 60 NEW COAL HNDLINGPLANT (NCHP) KEYDIAGRAM
61. 61 The main constituents of NCHP plant are:- Most of the constituents of the NCHP
are the same as that of OCHP. WAGONTIPPLER InNCHPthereisonlyone
wagontippler.Inthisittakes52sectoraisea wagon,10secto emptythe
wagoncompletely&thenagain52sectobringthetippler down.AsemicircularhugeWTgear is
used to run the tippler. Protocol cameras have been installed for safety to ensure that
nomoving creatureor objectisnearthewagonwhichisonthetippler.
62. 62 COALFEEDERTO THEPLANT Vibro feedersareinstalledbelowthehopper
whichhelpsinputtingthecoaltotheconveyor belts. There are 2 conveyor belts & 3 vibro
feeder per plant, so in total there are 6 vibrofeeders. Given below are the feeder motor
specifications:
TURNINGPOINT-6BREAKER HOUSE This house is required to render the coal size to
100mm sq. A 415W LT motor is used in the breaker house. REJECTIONHOUSE
Thecoalcomestobreakerhousevia conveyor
belts12A&12B.Nowinthebreakerhousethehuge stones & metal impurities are separated &
sent to reject bin house through belts 18A &18B. RECLAIMHOPPER It is the stockyard
in which coal is stored for emergency purposes. Around 3 lakh ton of coal can
bestoredinit TURNINGPOINT 7 CRUSHERHOUSE To ensure that the coal is of
uniform size it is passed through crusher. The crusher is of ring type. Has a motor rating
of 400HP,606KV.It is designed to crush the pieces to 20mm size EXIT
63. 63 SEQUENTIALOPERATIONOFNCHP:- a) Coal arrives in wagons and tipples
into hoppers. b) if the coal is oversized (400mm sq), then it is broken manually so that it
passes through the hopper mesh. c) From hopper it is taken to TP-6 12A & 12B. d)
Conveyors12A&12Btakethecoaltothebreakerhousewhichrendersthecoalsizetobe 100 mm
sq. e) Metalseparator &metaldetectorareinstalledinconveyor belts14A/B
&15A/Brespectivelyto removethemetalimpurities .f) Stones which are not able to pass
through the 100mm sq mesh of hammer are rejected via 18A & 18B to the rejection
house. g) Extra coal is sent to the reclaim hopper via conveyor 16A & 16B. h)From TP-7,
coal is taken by conveyor 14A & 14B to the crusher house whose function is to render
size of the coal to 20mm sq. SPECIFICATIONSOFMOTORSUSEDINNCHP:- I.
Crusher: - BHEL ILAT/12B HD/02, 736rpm, 550Kw, 6600V. II. WagonTippler:5D315l,98Kw slipringmotor. III. Conveyors: - 1)11A/B, 12A/B: - 125Kw, 315m,
1485rpm. 2)13A/B: - 55Kw, 250m, 1480rpm. 3)14A/B, 15A/B: - 150Kw, 355m,
1485rpm. 4)16A/B, 17A/B: - 110Kw, 315m, 1485rpm. 5)18A/B: - 37Kw, 225m,
1470rpm. IV. Rotary Breaker: - 110Kw, 315m, 1485rpm
64. 64 V. Belt Feeder: - 15Kw, 180L, 1445rpm VI. Reversible Belt Feeder: - 18.7Kw,
200L, 1485rp VII. VF 1-6: - 7.5Kw, 160m, 1485rpm VIII. VF 7-8: - 15Kw, 180L,
1485rpm IX. VF 9-12: - 11Kw,160L, 1485rpm X. WSP Crusher House: - 15Kw, 160m,
4000rpm XI. WSP Breaker House: - 7.5Kw, 132m, 1865rpm XII. Metal Separator: 5KV, 132m, 1410rpm XIII. Spray Precipitator: - 18.5Kw, 200L, 3000rpm
SAFETYDEVICESFORBELT CONVEYORS Sometimes the belt is wet due to any
reason, so it may not run due to reduced friction. A switch senses this and prevents the
belt from choking. Sometime any accident may occur which requires the belt to stop, the
pull cords are pulled to stop the conveyor. This system starts again only when the pull
cords are rest. There is a push button in the control room from where the belt can be
stopped in case of emergency stoppage. Other equipments are pulley. Pulleys are made of
mild steel, rubber logging is provided to increase the friction factor between the pulley
and belt. MILLINGSYSTEM 1. RCBUNKER Raw coal is fed directly to these bunkers.
These are 3 in no. per boiler. 4 & ½ tons of coal are fed in 1 hr. the depth of bunkers is
10m.
65. 65 2. RCFEEDER 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. BALLMILL: 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. In
ball mill coal is converted to powdered form and due to pneumatic action the powdered
form of coal is transferred upwards. 4. CLASSIFIER: It is equipment which serves
separation of fine pulverized coal particles medium from coarse medium. The pulverized
coal along with the carrying medium strikes the impact plate through the lower part.
Large particles are then transferred to the ball mill. 5. MILLFAN From ball mill the
powdered coal is sucked through mill fan. 6. CYCLONESEPARATORS It separates the
pulverized coal from carrying medium. The mixture of pulverized coal vapour caters the
cyclone separators tangentially in the upper part of the separator. Due to decrease in the
velocity the centrifugal action, the pulverized coal separated from the vapour
&fallsdowntothelower epicalpart.
66. 66 7. THETURNIGATE It serves to transport pulverized coal from cyclone
separators to pulverized coal bunker or to worm conveyors. There are 4 turnigates per
boiler. 8. WORMCONVEYOR It is equipment used to distribute the pulverized coal
from bunker of one system to bunker of other system. It can be operated in both
directions
67. 67 ELECTRICAL MAINTENANCE DEPARTMENT –II (EMD-II) Electrical
assigned to do training in this division from 2nd July to13th July.
68. 68 GENERATORS The generator works on the principle of electromagnetic
induction. There are two components stator and rotor. The rotor is the moving part and
the stator is the stationary part. The rotor, which has a field winding, is given a excitation
through a set of 3000rpm to give
therequiredfrequencyofHZ.TherotoriscooledbyHydrogengas,whichislocally manufactured
by the plant and has high heat carrying capacity of low density. If oxygen and
hydrogengetmixedthentheywillformveryhighexplosiveandtopreventtheir combininginany
waythereissealoilsystem.Thestator coolingisdonebyde-mineralized(DM)
waterthroughhollow conductors.WaterisfedbyoneendbyTeflontube.Aboilerandaturbineare
coupled to electric generators. Steam from the boiler is fed to the turbine through the
connecting pipe. Steam drives the turbine rotor. The turbine rotor drives the generator
rotor which turns the electromagnet within the coil of wire conductors. Carbon dioxide is
provided from the top and oil is provided from bottom to the generator. With
thehelpofcarbondioxidetheoilisdrainedouttotheoiltank.
sed
Clarified water in cooling tower is used to cool down the hydrogen gas.
TURBOGENERATOR210MW The 100 MW generator generates 10.75 KV and 210
MW generates 15.75 KV. The voltage is steppedupto220KVwiththehelpofgenerator
transformerandisconnectedtothegrid. Thevoltageissteppeddownto6.6
KVwiththehelpofUNIT AUXILLARY TRANSFORMER (UAT)and this voltage is used
to drive the HT motors. The voltage is further stepped down to 415 V and then to 220 V
and this voltage is used to drive Lt Motors.
70. 70 TURBOGENERATOR100MW MAKE BHEL, Haridwar CAPACITY 117,500
KVA POWER 100,000 KW STATOR VOLTAGE 10,500 V STATOR CURRENT 6475
A SPEED 5000rpm POWER FACTOR 0.85 FREQUENCY 50 HZ EXCITATION 280 V
TURBOGENERATOR210MW MAKE BHEL, Haridwar CAPACITY 247,000 KVA
POWER 210,000 KW STATOR VOLTAGE 15,750 V STATOR CURRENT 9050 A
SPEED 5000 rpm POWER FACTOR 0.85 FREQUENCY 50 HZ EXCITATION 310 V
GAS PRESSURE 3.5 kg/cm
71. 71 TRANSFORMERS INTRODUCTION It is a static machine which increases or
decreases the AC voltage without changing the frequency of the supply. It is a device
this by
influence of each other. WORKINGPRINCIPLE: It works on FARADAY‟S LAW OF
ELECTROMAGNETIC INDUCTION (self or mutual induction depending on the type of
transformer).
property of the oil from deterioration& protect the transformer against failure on account
entry
GASOPERATEDRELAY(BUCHHOLZRELAY) It is a gas actuated relay used for
protecting oil immersed transformer against all types of faults. It indicates presence of
gases in case of some minor fault & take out the transformer out of circuit in case of
bring out the terminals of the transformer from the container. The bushings are of 3 types:
a. Porcelain bushings used for low voltage transformer b. Oil filled bushings used for
OILGUAGE Every transformer with an oil guage to indicate the oil level. The oil guage
may be provided with the alarm contacts which gave an alarm the oil level has dropped
provided with few tappings on secondary side so that output voltage can be varied for
constant inp
GUAGE) Device which indicates the temperature of winding of transformer & possible
damage to the transformer due too overload can be prevented.
For the above reason it is also called cold-rolled steel instead hotHigh flux densities (1.4 to 1.7 Wb/sq m) are used in the core of power transformer which
CLASSIFICATION: (I) ACCORDINGTOTHECORE: a) Core type transformer b) shell
type transformer c) Berry type transformer (II) ACCORDINGTOPHASES: a) 1phase
transformer b) 3phase transformer (III)
ACCORDINGTOTHEPURPOSEFORWHICHUSED : a) Distribution transformer b)
Transmission transformer c) Generator transformer d) Station transformer e) Unit
Auxiliary transformer (UAT)
74. 74 COOLING OFTRANSFORMERSOF LARGEMVA: As size of transformer
becomes large, the rate of the oil circulating becomes insufficient to dissipate all the heat
produced & artificial means of increasing the circulation by electric pumps. In very large
transformers, special coolers with water circulation may have to be employed.
TYPESOFCOOLING: Air cooling 1. Air Natural (AN) 2. Air Forced (AF) Oil immersed
cooling 1. Oil Natural Air Natural (ONAN) 2. Oil Natural Air Forced (ONAF) 3. Oil
Forced Air Natural (OFAN) 4. Oil Forced Air Forced (OFAF) Oil immersed Water
cooling 1. Oil Natural Water Forced (ONWF) 2. Oil Forced Water Forced (OFWF)
MAINPARTSOFTRANSFORMER i. Secondary Winding ii. Primary Winding. iii. Oil
Level iv. Conservator v. Breather vi. Drain Cock vii. Cooling Tubes. viii. Transformer
Oil.
75. 75 ix. Earth Point x. Explosion Vent xi. Temperature Gauge. xii. Buchholz Relay xiii.
Secondary Terminal xiv. Primary Terminal
GENERATORTRANSFORMER(125MVAUNIT-I&UNIT-III) RATING 125MVA
TYPE OF COOLING OFB TEMP OF OIL 45^C TEMP WINDING 60^C KV (no load)
HV-233 KVA LV-10.5 KVA LINE AMPERES HV-310 A LV-6880 PHASE THREE
FREQUENCY 50 HZ IMPEDANCE VOLTAGE 15% VECTOR GROUP Y DELTA
INSULATION LEVEL HV-900 KV LV-Neutral-38 CORE AND WINDING WEIGHT
110500 Kg WEIGHT OF OIL 37200 Kg TOTAL WEIGHT 188500 Kg OIL
QUANTITY 43900 lit
76. 76 GENERATORTRANSFORMER (166MVA UNIT-IV) RATING 240MVA TYPE
OF COOLING ON/OB/OFB TEMP OF OIL TEMP WINDING VOLTS AT NO LOAD
HV-236000 LV-A5750 LINE AMPERES HV-587 A LV-8798 PHASE THREE
FREQUENCY 50 HZ IMPEDANCE VOLTAGE 15.55% VECTOR GROUP Y DELTA
CORE AND WINDING WEIGHT 138800 Kg WEIGHT OF OIL 37850 Kg TOTAL
WEIGHT 234000 Kg OIL QUANTITY 42500 lit GUARANTEED MAX TEMP
DIVISION KERELA YEAR 1977
77. 77 UNIT AUXILIARY TRANSFORMER(UAT) Unit I & V- 12.5 MVA The UAT
draws its input from the main bus-ducts. The total KVA capacity of UAT required can be
determined by assuming 0.85 power factor & 90% efficiency for total auxiliary motor
load. It is safe & desirable to provide about 20% excess capacity then circulated to
provide for miscellaneous auxiliaries & possible increase in auxiliary. STATION
TRANSFORMER It is required to feed power to the auxiliaries during startups. This
transformer is normally rated for initial auxiliary load requirements of the unit in typical
cases; this load is of the order of 60% of the load at full generating capacity. It is
provided with on load tap change to cater to the fluctuating voltage of the grid.
NEUTRALGROUNDED TRANSFORMER This transformer is connected with supply
coming out of UAT in stage-2. This is used to ground
theexcessvoltageifoccursinthesecondaryofUATinspiteofratedvoltage.
78. 78 SWITCH YARD As we know that electrical energy can‟t be stored like cells, so
what we generate should be
consumedinstantaneously.Butastheloadisnotconstantsthereforewegenerateelectricityaccor
ding toneedi.e.thegenerationdependsuponload.Theyardistheplacesfromwheretheelectricity
is send outside. It has both outdoor and indoor equipments. OUTDOOREQUIPMENTS i.
BUSBAR. ii. LIGHTENINGARRESTER iii. WAVETRAP iv. BREAKER v.
CAPACITATIVEVOLTAGETRANSFORMER vi. EARTHINGROD vii.
CURRENTTRANSFORMER. viii. POTENTIALTRANSFORMER ix.
LIGHTENINGMASK INDOOREQUIPMENTS i. RELAYS. ii. CONTROLPANELS iii.
CIRCUITBREAKERS
79. 79
IS-5082 or copper of adequatecrosssection.Busbarlocatedinair
insulatedenclosures&segregated fromallother components.Busbar ispreferablycover
ackupbuswhichcomeshandy
whenanyofthebusesbecome faulty.Whenany
operationbushasfault,thisbusisbroughtintocircuitandthenfaultylineisremovedthereby
reactor from over voltage and over currents. It grounds the overload
ifthereisfaultonthelineanditpreventsthegenerator transformer.The
practiceistoinstalllighteningarrestorattheincomingterminaloftheline.Wehavetouse the
lightningarrester bothinprimaryandsecondaryoftransformerandinreactors.A meter is
providedwhichindicatesthesurfaceleakageandinternalgradingcurrentofarrester.
TRAP Power line carrier communication (PLCC) is mainly used for telecommunication,
tele-protection and tele-monitoring between electrical substations through power lines at
high voltages, such as 110 kV, 220 kV, and 400 kV. PLCC integrates the transmission of
communication signal and 50/60 Hz power signal through the same electric power cable.
The major benefit is the union of two important applications in a single system.
WAVETRAP is connected in series with the power (transmission) line. It blocks the high
frequency carrier waves (24 KHz to 500 KHz) and let power waves (50 Hz - 60 Hz) to
pass-through.
80. 80
flowofcurrent.Acircuit breaker instationservesthesamepurposeasswitchbutithas
manyaddedandcomplex features. The basic construction of any circuit breaker requires
the separation of contact in an insulating fluid that servers two functions: i.
extinguishesthearcdrawnbetweenthecontactswhencircuitbreaker opens. ii.
CAPACITATIVE VOLTAGETRANSFORMER A capacitor voltage transformer (CVT)
is a transformer used in power systems to step-down extra high voltage signals
andprovidelow voltage signals either for measurement or to operatea
protectiverelay.Itislocatedinthelastintheswitchyardasit increasestheground resistance.
Finally the voltage from CVT in the switchyard is sent out from the station through
-galvanizedmildsteelflatsareusedfor
earthling.Separateearthingelectrodesare provided to earth the lightening arrestor whereas
the other equipments are earthed by connectingtheir earthleadstotherid/ser
which step down the current to a known ratio. It is a type of instrument transformer
designed to provide a current in its secondary winding proportional to the alternating
current flowing in its primary.
sensing device that makes your circuit ON or OFF. They detect the abnormal
conditionsintheelectricalcircuitsbycontinuouslymeasuringtheelectricalquantities,
whicharedifferentundernormalandfaultyconditions,likecurrent,voltagefrequency.Having
detectedthefaulttherelayoperatestocompletethetripcircuit, whichresultsintheopening of the
circuit breakers and disconnect the faulty circuit. Therearedifferenttypesofrelays: i.
Currentrelay ii. Potentialrelay iii. Electromagneticrelay iv. Numericalrelayetc.
AIRBREAK EARTHINGSWITCH Thework
ofthisequipmentcomesintopicturewhenwewanttoshutdownthesupplyfor maintenance
purpose. This help to neutralize the system from induced voltage from extra high voltage.
This induced power is up to 2KV in case of 400 KV lines.
PRECIPITATOR An electrostatic precipitator ( ESP) or electrostatic air cleaner is a
particulate collection 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 that minimally impede the flow of gases through the device, and can
easily remove fine particulate matter such as dust and smoke from the air stream.
82. 82 In contrast to wet scrubbers which apply energy directly to the flowing fluid
medium, an ESP applies energy only to the particulate matter being collected and
therefore is very efficient in its consumption of energy (in the form of electricity).The
most basic precipitator contains a row of thin vertical wires, and followed by a stack of
large flat metal plates oriented vertically, with the plates typically spaced about 1 cm to18
cm apart, depending on the application. The air or gas stream flows horizontally through
the spaces between the wires, and then passes through the stack of plates. A negative
voltage of several thousand volts is applied between wire and plate. If the applied voltage
is high enough an electric (corona) discharge ionizes the gas around the electrodes.
Negative ions flow to the plates and charge the gas-flow particles. The ionized particles,
following the negative electric field created by the power supply, move to the grounded
plates. Particles build up on the collection plates and form a layer. The layer does not
collapse, thanks to electrostatic pressure (given from layer resistivity, electric field, and
current flowing in the collected layer).
INTRODUCTION This division basically calibrates various instruments and takes care
of any faults occur in any of the auxiliaries in the plant. “Instrumentation can be well
defined as a technology of using instruments to measure and control the physical and
chemical properties of a material.” C&I LABS Control and Instrumentation Department
s Safety Supervisory
System Lab
84. 84 OPERATION AND MAINTAINANCE Control and Instrumentation Department
has following Control Units: 1. Unit Control Board2. 2. Main Control Board3. 3. Analog
& Digital Signal Control4. 4. Current Signal Control
Thisdepartmentisthebrainoftheplantbecausefrom therelaystotransmittersfollowedbythe
electroniccomputationchipsetsandrecordersandlastlythecontrollingcircuitry,allfallunder
this. A View of Control Room at BTPS
85. 85 1. 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 It‟s 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 It‟s 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. While selecting Pressure Gauge these parameters should keep in mind- 1.
Accuracy 2. Safety 3. Utility 4. Price ACCURACY Higher Accuracy implies Larger Dial
Size for accuracy of small and readable pressure scale increments. SAFETY While
selecting Pressure Gauge it should consider that Gauge Construction Material should be
chemically compatible with the environment either inside or outside it.
86. 86 UTILITY It should keep it mind that range of the Gauge should be according to
our need else Overpressure Failure may occur resulting in damage of Gauge. PRICE
Lager the Gauge‟s Dial size larger would be our price. Better Gauge‟s Construction
material also increases the cost. So they must be chosen according to our need. 2.
PROTECTION AND INTERLOCKING INTERLOCKING It is basically
interconnecting two or more equipments so that if one equipment 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, which trips the
circuit. The main equipments of this lab are relay and circuit breakers. Some of the
instrument uses for protection are: 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 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.
87. 87 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 vaporization quicker than any other material
because of its comparatively low specific heat. 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 trips. I. MANUAL TRIP II. THERMAL TRIP III.
SHORT CIRCUIT TRIP Protection and Interlock System- 1) HIGH TENSION
CONTROL CIRCUIT for high tension system the control system is 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.
88. 88 3. 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. 4.
PYROMETRY LAB LIQUID IN GLASS THERMOMETER Mercury in the glass
thermometer boils at 340° C which limits the range of temperature that can be measured.
It is L shaped thermometer which is designed to reach all inaccessible places. 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. 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.
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) .
89. 89 5. 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°C and its heights 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 no circumstances should anyone be left out under operation,
to Prevent creation of pressure different with in the furnace, which threatens to blast it. 6.
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. 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.
90. 90 CONTROL & MONITORING MECHANISMS There are basically two types of
Problems faced in a Power Plant 1. Metallurgical 2. Mechanical Mechanical Problem can
be related to Turbines that is the max speed permissible for a turbine is3000 rpm so speed
should be monitored and maintained at that level. Metallurgical Problem can be view as
the max Inlet Temperature for Turbine is 1060° C so temperature should be below the
limit. Monitoring of all the parameters is necessary for the safety of both: 1. Employees
2. Machines So the Parameters to be monitored are: 1. Speed 2. Temperature 3. Current
4. Voltage 5. Pressure 6. Eccentricity 7. Flow of Gases 8. Vacuum Pressure 9. Valves 10.
Level 11. Vibration
91. 91 PRESSURE MONITORING Pressure can be monitored by three types of basic
mechanisms 1. Switches 2. Gauges 3. Transmitter type For gauges we use Bourdon tubes.
The Bourdon Tube is a non-liquid pressure measurement device. It is widely used in
applications where inexpensive static pressure measurements are needed. A typical
Bourdon tube contains a curved tube that is open to external pressure input on one end
and is coupled mechanically to an indicating needle on the other end, as shows
schematically below. Typical Bourdon Tube Pressure Gages For Switches pressure
switches are used and they can be used for digital means of monitoring as switch being
ON is referred as high and being OFF is as low. All the monitored data is converted to
either Current or Voltage parameter.
92. 92 The Plant standard for current and voltage are as under • Voltage : 0 –10 Volts
range • Current : 4 –20milli-Amperes We use 4mA as the lower value so as to check for
disturbances and wire breaks. Accuracy of such systems is very high.
ACCURACY:±0.1% Programmable Logic Circuits (PLCs) are used in the process as
they are the heart of Instrumentation.
93. 93 TEMPERATURE MONITORING We can use Thermocouples or RTDs for
temperature monitoring. Normally RTDs are used for low temperatures. Thermocouple
selection depends upon two factors: 1. TemperatureRange 2. Accuracy Required
Normally used Thermocouple is KTypeThermocouple: In this we use Chromel (NickelChromium Alloy) / Alumel (Nickel-Aluminium Alloy) as two metals. This is the most
commonly used general purpose thermocouple. It is inexpensive and, owing to its
popularity, available in a wide variety of probes. They are available in the−200°C to
+1200°C range. Sensitivity is approximately 41 μV/°C. RTDs are also used but not in
protection systems due to vibrational errors. We pass a constant current through the RTD.
So that if R changes then the Voltage also changes RTDs used in Industries are Pt100
And Pt1000 Pt100: 0°C – 100 Ω ( 1 Ω = 2.5 0C ) Pt1000: 0°C - 1000Ω Pt1000 is used for
higher accuracy. The gauges used for Temperature measurements are mercury filled
Temperature gauges. For Analog medium thermocouples are used and for Digital
medium Switches are used which are basically mercury switches.
94. 94 FLOWMEASUREMENT Flow measurement does not signify much and is
measured just for metering purposes and for monitoring the processes ROTAMETERS:
A Rotameter is a device that measures the flow rate of liquid or gas in a closed tube. It is
occasionally misspelled as 'Rotometer'. It belongs to a class of meters called variable area
meters, which measure flow rate by allowing the cross sectional area the fluid travels
through to vary, causing some measurable effect. A rotameter consists of a tapered tube,
typically made of glass, with a float inside that is pushed up by flow and pulled down by
gravity. At a higher flow rate more area (between the float and the tube) is needed to
accommodate the flow, so the float rises. Floats are made in many different shapes, with
spheres and spherical ellipses being the most common. The float is shaped so that it
rotates axially as the fluid passes. This allows you to tell if the float is stuck since it will
only rotate if it is not. For Digital measurements Flap system is used. For Analog
measurements we can use the following methods : 1. Flow meters 2. Venturimeters /
Orifice meters 3. Turbines 4. Massflowmeters(oil level) 5. UltrasonicFlowmeters 6.
Magnetic Flow meter (water level ) Selection of flow meter depends upon the purpose,
accuracy and liquid to be measured so different types of meters used.
95. 95 TURBINE TYPE: They are simplest of all. They work on the principle that on
each rotation of the turbine a pulse is generated and that pulse is counted to get the flow
rate. VENTURIMETERS : Referring to the diagram, using Bernoulli's equation in the
special case of incompressible fluids (such as the approximation of a water jet), and the
theoretical pressure drop at the constriction would be given by (ρ/2)(v2 2 - v1 2 ). And
we know that rate of flow is given by: Flow= k√(D.P) Where DP is Differential Pressure
or the Pressure Drop.
96. 96 CONTROL VALVES A valve is a device that regulates the flow of substances
(either gases, fluidized solids, slurries, or liquids) by opening, closing, or partially
obstructing various passageways. Valves are technically pipe fittings, but usually are
discussed separately. Valves are used in a variety of applications including industrial,
military, commercial, residential, transportation. Plumbing valves are the most obvious in
everyday life, but many more are used. Some valves are driven by pressure only, they are
mainly used for safety purposes in steam engines and domestic heating or cooking
appliances. Others are used in a controlled way, like in Otto cycle engines driven by a
camshaft, where they play a major role in engine cycle control. Many valves are
controlled manually with a handle attached to the valve stem. If the handle is turned a
quarter of a full turn (90°) between operating positions, the valve is called a quarter-turn
valve. Butterfly valves, ball valves, and plug valves are often quarter-turn valves. Valves
can also be controlled by devices called actuators attached to the stem. They can be
electromechanical actuators such as an electric motor or solenoid, pneumatic actuators
which are controlled by air pressure, or hydraulic actuators which are controlled by the
pressure of a liquid such as oil or water. So there are basically three types of valves that
are used in power industries besides the handle valves. They are :· PNEUMATIC
VALVES –They are air or gas controlled which is compressed to turn or move them·
HYDRAULIC VALVES – They utilize oil in place of Air as oil has better compression·
MOTORISED VALVES – These valves are controlled by electric motors
97. 97 FURNACE SAFEGUARD SUPERVISORY SYSTEM FSSS is also called as
Burner Management System (BMS). It is a microprocessor Based programmable logic
controller of proven design incorporating all protection facilities required for such
system. Main objective of FSSS is to ensure safety of the boiler. The 95 MW boilers are
indirect type boilers. Fire takes place in front and in rear side. That‟s why it‟s called front
and rear type boiler. The 210 MW boilers are direct type boilers (which means that HSD
is in direct contact with coal) firing takes place from the corner. Thus it is also known as
corner type boiler. IGNITER SYSTEM Igniter system is an automatic system, it takes the
charge from 110kv and this spark is brought in front of the oil guns, which spray aerated
HSD on the coal for coal combustion. There is a 5 minute delay cycle before igniting, this
is to evacuate or burn the HSD. This method is known as PURGING. PRESSURE
SWITCH Pressure switches are the devices that make or break a circuit. When pressure is
applied, the switch under the switch gets pressed which is attached to a relay that makes
or break the circuit. Time delay can also be included in sensing the pressure with the help
of pressure valves. Examples of pressure valves: 1. Manual valves (tap) 2. Motorized
valves (actuator) –works on motor action 3. Pneumatic valve (actuator) - works due to
pressure of compressed air 4. Hydraulic valve