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8/13/2019 Pp Soft Copy

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POWER

PLANT


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JNIL, SPD, SILTARA,RAIPUR

OPERATION&

MECHANICAL


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POWER PLANT

A thermal power stationis apower plant in which theprime mover issteam driven. Water is

heated, turns into steam and spins asteam turbine which drives anelectrical generator.After it

passes through the turbine, the steam is condensed in acondenser and recycled to where it was

heated; this is known as aRankine cycle.The greatest variation in the design of thermal powerstations is due to the different fuel sources. Some prefer to use the term energy centerbecause

such facilities convert forms of heat energy into electricity.[1]

Some thermal power plants also

deliver heat energy for industrial purposes, for district heating, or for desalination of water as

well as delivering electrical power. A large part of human CO 2 emissions comes from fossil

fueled thermal power plants; efforts to reduce these outputs are various and widespread

RANKINE CYCLE

There are four processes in the Rankine cycle. These states are identified by numbers (in brown)

in the above Ts diagram.

Process 1-2: The working fluid is pumped from low to high pressure. As the fluid is aliquid at this stage the pump requires little input energy.

Process 2-3: The high pressure liquid enters a boiler where it is heated at constantpressure by an external heat source to become a dry saturated vapor.

Process 3-4: The dry saturated vapor expands through a turbine, generating power. Thisdecreases the temperature and pressure of the vapor, and some condensation may occur.

Process 4-1: The wet vapor then enters a condenser where it is condensed at a constanttemperature to become a saturated liquid.
http://en.wikipedia.org/wiki/Power_planthttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Thermal_power_station#cite_note-1http://en.wikipedia.org/wiki/Thermal_power_station#cite_note-1http://en.wikipedia.org/wiki/Thermal_power_station#cite_note-1http://en.wikipedia.org/wiki/District_heatinghttp://en.wikipedia.org/wiki/Desalinationhttp://en.wikipedia.org/wiki/Desalinationhttp://en.wikipedia.org/wiki/District_heatinghttp://en.wikipedia.org/wiki/Thermal_power_station#cite_note-1http://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steamhttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Power_plant


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DIAGRAM OF A TYPICAL COAL THERMAL POWER STATION:-

Typical diagram of a coal-fired thermal power station

1.Cooling tower 10. SteamControl valve 19.Superheater

2. Cooling water pump 11. High pressuresteam turbine 20. Forced draught (draft)fan

3.transmission line (3-phase) 12.Deaerator 21. Reheater

4. Step-uptransformer (3-phase) 13.Feedwater heater 22.Combustion air intake

5.Electrical generator (3-phase) 14.Coalconveyor 23.Economiser

6. Low pressuresteam turbine 15.Coal hopper 24.Air preheater

7.Condensate pump 16.Coal pulverizer 25.Precipitator

8.Surface condenser 17.Boiler steam drum 26. Induced draught (draft)fan

9. Intermediate pressure steam 18.Bottom ash hopper 27.Flue gas stack
http://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Control_valvehttp://en.wikipedia.org/wiki/Control_valvehttp://en.wikipedia.org/wiki/Superheaterhttp://en.wikipedia.org/wiki/Superheaterhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Electrical_power_transmissionhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Deaeratorhttp://en.wikipedia.org/wiki/Deaeratorhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Feedwater_heaterhttp://en.wikipedia.org/wiki/Feedwater_heaterhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Conveyorhttp://en.wikipedia.org/wiki/Conveyorhttp://en.wikipedia.org/wiki/Economiserhttp://en.wikipedia.org/wiki/Economiserhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Condensate_pumphttp://en.wikipedia.org/wiki/Condensate_pumphttp://en.wikipedia.org/wiki/Pulverizerhttp://en.wikipedia.org/wiki/Pulverizerhttp://en.wikipedia.org/wiki/Electrostatic_precipitatorhttp://en.wikipedia.org/wiki/Electrostatic_precipitatorhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Steam_drumhttp://en.wikipedia.org/wiki/Steam_drumhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Bottom_ashhttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/File:PowerStation2.svghttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/Bottom_ashhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Steam_drumhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Electrostatic_precipitatorhttp://en.wikipedia.org/wiki/Pulverizerhttp://en.wikipedia.org/wiki/Condensate_pumphttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Economiserhttp://en.wikipedia.org/wiki/Conveyorhttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Feedwater_heaterhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Deaeratorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Electrical_power_transmissionhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Superheaterhttp://en.wikipedia.org/wiki/Control_valvehttp://en.wikipedia.org/wiki/Cooling_tower


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BOILER

A boiler is used to generate steam at a desired pressure and temperature by transferring heatproduced by burning fuel to water to change it to steam.

Steam is used for the following purposes:

Power generation Processing Heating

REQUIREMENTS OF AN EFFICIENT BOILER

1) Should generate maximum amount of steam at a required pressure and temperature and

quality with minimum fuel consumption.2) Should be light in weight and should not occupy large space.

3) Should conform to safety regulations.4) Should have low initial cost, installation cost and maintenance cost.

5) Should be able to cope with fluctuating demands of steam supply.6) All parts and components should be easily accessible for inspection and repair.

TYPES OF BOILER

FIRE TUBE BOILERIn fire tube boiler, hot gases pass through the tubes and boiler feed water in the shell side isconverted into steam. Fire tube boilers are generally used for relatively small steam capacities

and low to medium steam pressures. Fire tube boilers are available for operation with oil, gas orsolid fuels. For economic reasons, most fire tube boilers are nowadays of packaged

construction (i.e. manufacturers shop erected) for all fuels.

WATER TUBE BOILERIn water tube boiler, boiler feed water flows through the tubes and enters the boiler drum. The

circulated water is heated by the combustion gases and converted into steam at the vapour space

in the drum. These boilers are selected when the steam demand as well as steam pressure

requirements are high as in the case of process cum power boiler / power boilers

Many water tube boilers nowadays are of packaged construction if oil and /or gas are to be

used as fuel. Solid fuel fired water tube designs are available but packaged designs are lesscommon.


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The features of water tube boilers are:-

Forced, induced and balanced draft provisions help to improve combustion efficiency. Less tolerance for water quality calls for water treatment plant. Higher thermal efficiency shifts are possible

In JNIL we use water tube boiler.

ATMOSPHERIC FLUIDIZED BED COMBUSTION (AFBC) BOILER

Most operational boiler of this type is of the Atmospheric Fluidized Bed Combustion. (AFBC).

This involves little more than adding a fluidized bed combustor to a conventional shell boiler.Such systems have similarly being installed in conjunction with conventional water tube boiler.

Coal is crushed to a size of 110 mm depending on the rank of coal, type of fuel fed to the

combustion chamber. The atmospheric air, which acts as both the fluidization and combustion

air, is delivered at a pressure, after being preheated by the exhaust fuel gases. The in-bed tubescarrying water generally act as the evaporator. The gaseous products of combustion pass over thesuper heater sections of the boiler flow past the economizer, the dust collectors and the air

preheater before being exhausted to atmosphere.

WASTE HEAT BOILER

Wherever the waste heat is available at medium or high temperatures, a waste heat boiler can beinstalled economically. Wherever the steam demand is more than the steam generated during

waste heat, auxiliary fuel burners are also used. If there is no direct use of steam, the steam maybe let down in a steam turbine-generator set and power produced from it. It is widely used in the

heat recovery from exhaust gases from gas turbines and diesel engines

BOILER MOUNTINGS AND ACCESSORIES

Boilers are equipped with two categories of components: boiler mountings and boiler

accessories. Boiler mountings are the machine components that are mounted over the body of the

boiler itself for the safety of the boiler and for complete control of the process of steam

generation. Boiler accessories are those components which are installed either inside or outside

the boiler to increase the efficiency of the plant and to help in the proper working of the plant.


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Boiler Mountings Function

1.Two safety valves To permit the steam in the boiler to escape to atmosphere when pressure inthe steam space exceeds a certain specified limit.

2.Two water level

indicators

To ascertain constantly and exactly the level of water in the boiler shell

3.

Pressure gauge

To record the pressure at which the steam is generated in the boiler

4.

Fusible plug

To extinguish fire in the event of water level in the boiler shell fallingbelow a certain specified limit.

5.

Steam stop valve

To shut off or regulate the flow of steam from the boiler to the steam pipe

or from the steam pipe to the engine

6.

Feed check valve

i) To allow the feed water to pass into the boiler.ii) To prevent the back flow of water from the boiler in the event of thefailure of the feed pump

7.

Blow-off cock

To drain out the water from the boiler for internal cleaning, inspection

or other purposes.

8.

Man and mud holes

To allow men to enter inside the boiler for inspection and repair.


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Boileraccessories

Function

1.Air preheater Waste heat recovery device in which the air to on its way to the furnace is heated

utilizing the heat of exhaust gases

2.Economizer To recover some of the heat being carried over by exhaust gases (This heat isused to raise the temperature of feedwater supplied to the boiler)

3.

Steam

superheater

To superheat the steam generated by boiler

4.

Feed pump

To raise the pressure of water and force it into the boiler

5.

Injector

To feed water in vertical and locomotive boilers

CONTROLLING DRAUGHT

Most boilers now depend on mechanical draught equipment rather than natural draught. This isbecause natural draught is subject to outside air conditions and temperature of flue gases leaving

the furnace, as well as the chimney height. All these factors make proper draught hard to attainand therefore make mechanical draught equipment much more economical.

There are three types of mechanical draught:

INDUCED DRAUGHT:This is obtained one of three ways, the first being the "stackeffect" of a heated chimney, in which the flue gas is less dense than the ambient airsurrounding the boiler. The denser column of ambient air forces combustion air into and

through the boiler. The second method is through use of a steam jet. The steam jetoriented in the direction of flue gas flow induces flue gasses into the stack and allows for

a greater flue gas velocity increasing the overall draught in the furnace. This method wascommon on steam driven locomotives which could not have tall chimneys. The third

method is by simply using an induced draught fan (ID fan) which removes flue gasesfrom the furnace and forces the exhaust gas up the stack. Almost all induced draught

furnaces operate with a slightly negative pressure.

FORCED DRAUGHT:Draught is obtained by forcing air into the furnace by means ofa fan (FD fan) and ductwork. Air is often passed through an air heater; which, as thename suggests, heats the air going into the furnace in order to increase the overall

efficiency of the boiler. Dampers are used to control the quantity of air admitted to thefurnace. Forced draught furnaces usually have a positive pressure.


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BALANCED DRAUGHT:Balanced draught is obtained through use of both inducedand forced draught. This is more common with larger boilers where the flue gases have to

travel a long distance through many boiler passes. The induced draught fan works inconjunction with the forced draught fan allowing the furnace pressure to be maintained

slightly below atmospheric.

DEAERATOR

A Deaerator is a device that is widely used for the removal of oxygen and other dissolvedgases from thefeedwater to steam-generatingboilers.In particular, dissolvedoxygen in

boiler feedwaters will cause serious corrosion damage in steam systems by attaching to thewalls of metal piping and other metallic equipment and formingoxides (rust). Dissolved

carbon dioxide combines with water to formcarbonic acid that causes further corrosion.

DESUPERHEATER

Desuperheater are designed to reduce the temperature of super heated steam to produce loweroperating temperatures. desuperheater is used because Reduction and control of super heatedsteam, will not harm the product.

ECONOMIZER

Economizers are heat exchange devices that heat fluids, usually water, up to but not normally beyond

theboilingpoint of that fluid. Economizers are so named because they can make use of theenthalpyin fluid streams that are hot, but not hot enough to be used in a boiler, thereby recovering more useful

enthalpy and improving the boiler's efficiency. They are a device fitted to a boiler which saves energy

by using the exhaust gases from the boiler to preheat the cold water used to fill it (thefeed water).

SUPERHEATER

A Superheater is a device used to convertsaturated steamor wet steam into dry steamused in TURBINE. Superheaters increase thethermal efficiency of the turbine, and have

been widely adopted.
http://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Feedwaterhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Oxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbonic_acidhttp://en.wikipedia.org/wiki/Boilinghttp://en.wikipedia.org/wiki/Enthalpyhttp://en.wikipedia.org/wiki/Boiler_feedwaterhttp://en.wikipedia.org/wiki/Boiler_feedwaterhttp://en.wikipedia.org/wiki/Boiler_feedwaterhttp://en.wikipedia.org/wiki/Thermal_efficiencyhttp://en.wikipedia.org/wiki/Thermal_efficiencyhttp://en.wikipedia.org/wiki/Boiler_feedwaterhttp://en.wikipedia.org/wiki/Enthalpyhttp://en.wikipedia.org/wiki/Boilinghttp://en.wikipedia.org/wiki/Carbonic_acidhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Oxidehttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Feedwaterhttp://en.wikipedia.org/wiki/Gas


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TURBINE

A turbineis a rotary mechanical device that extractsenergy from afluid flow and converts itinto usefulwork.A turbine is aturbomachine with at least one moving part called a rotor

assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so thatthey move and impart rotational energy to the rotor. Early turbine examples arewindmills and

water wheels.The Turbines are mechanical energy convert into electrical energy. In practice,modern turbine designs use both reaction and impulse concepts to varying degrees whenever

possible. Like we use in JNIL plan.
http://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Work_(physics)http://en.wikipedia.org/wiki/Turbomachineryhttp://en.wikipedia.org/wiki/Windmillhttp://en.wikipedia.org/wiki/Water_wheelhttp://en.wikipedia.org/wiki/Water_wheelhttp://en.wikipedia.org/wiki/Windmillhttp://en.wikipedia.org/wiki/Turbomachineryhttp://en.wikipedia.org/wiki/Work_(physics)http://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Energy


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CONDENSER

In power plants, the primary purpose of a surface condenser is to condense the exhaust steam

from a steam turbine to obtain maximumefficiency and also to convert the turbine exhaust steam

into pure water (referred to as steam condensate) so that it may be reused in the steam generator

orboiler as boiler feed water.. If the condenser can be made cooler, the pressure of the exhaust

steam is reduced and efficiency of the cycle increases. The condenser generally uses either

circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or once-through water from a river, lake or ocean. The heat absorbed by the circulating cooling water in

the condenser tubes must also be removed to maintain the ability of the water to cool as it

circulates. The surface condenser is a shell and tube heat exchanger in which cooling water is

circulated through the tubes. T he exhaust steam from the low pressure turbine enters the shell

where it is cooled and converted to condensate (water) by flowing over the tubes as shown in the

adjacent diagram. Such condensers use steam ejectors or rotary motor-driven exhausters for

continuous removal of air and gases from the steam side to maintainvacuum.
http://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Thermal_efficiencyhttp://en.wikipedia.org/wiki/Water-tube_boilerhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Shell_and_tube_heat_exchangerhttp://en.wikipedia.org/wiki/Injectorhttp://en.wikipedia.org/wiki/Rotary_motorhttp://en.wikipedia.org/w/index.php?title=Exhausters&action=edit&redlink=1http://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/w/index.php?title=Exhausters&action=edit&redlink=1http://en.wikipedia.org/wiki/Rotary_motorhttp://en.wikipedia.org/wiki/Injectorhttp://en.wikipedia.org/wiki/Shell_and_tube_heat_exchangerhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Water-tube_boilerhttp://en.wikipedia.org/wiki/Thermal_efficiencyhttp://en.wikipedia.org/wiki/Condensation


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COOLING TOWER

Thermal power plants use cooling towers to cool the circulating water used for condensercooling. Since water resources are limited, power plants have no other option but to adopt the

closed cooling system with cooling towers

Cooling towers can be of two types.

NATURAL DRAFT- cooling tower with a large hyperbolic tower, which pulls in air due tothe stack effect. Even though the capital costs are high, operating costs are less. This is

because there is no fan to create the air flow.

MECHANICAL OR FORCED COOLING TOWER- A fan forces or sucks air throughthe cooling tower where the water falls through a packed heat transfer media. Operating costs

are high for operating this, but they are simple and quick for construction.


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WATER FLOW PATH

DEAERATOR

BOILER FEED PUMP

ECONOMIZER

BOILER DRUM

MUD DRUM

PRIMARY SUPERHEATER

SECONDARY SUPERHEATER

TURBINE

CONDENSER

CONDENSATE EXTRACTION PUMP ( CEP)


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FLUE GAS PATH

FURNACE HEAT

SECONDARY SUPERHEATER

PRIMARY SUPERHEATER

ECONOMIZER

AIR PREHEATER

ELECTRO STATIC PRECIPITATOR ( ESP)

CHIMNEY


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WATER SOFTENING PATH

KHARUN DAM

STORAGE TANK

SOFTENING PLANT

BRINE EXCHANGER

DI-MEDIUM FILTER

STORAGE TANK

COOLING TOWER


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DEMINERALISED PLANT

FILTER FEED TANK

DI- MEDIUM FILTER

AQUOUS CARBON FILTER

STRONG ANION CATION

DEGASSER TANK

STRONG BASE ANION

MIXED BED

STORAGE TAN


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ELECTRICAL


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SPECIFICATION (JNIL)

In our JNIL Plant we are having Five Power Plants, mentioned as:-

JNIL POWER PLANT COKE OVEN POWER PLANT ABHIJEET INFRASTRUCTURE LIMITED (AIL) CORPORATE ISPAT AND ALLOY LIMITED (CIAL) MAA USHA URJA LIMITED.(MUUL)

A. JNIL POWER PLANT:-

In JNIL POWER PLANT we generate 15 MW/H power as having four boilers and three Turbo-

Generators. Three boilers are of WHRB type boilers and One boiler is of AFBC boilers. Thecomplete specifications of boilers are as follows:-

Steam Generation Capacity = ( 3 Nos of Oil/ Gas fired boilers & 1 No of AFBC boiler).

OIL/GAS FIRED BOILERS = 30*3 TPH

AFBC BOILERS = 30 TPH

Total Steam Generation = 120 TPH

Parameters as follows:-

Steam Temperature = 440` C

Pressure = 38.5 kg/cm2

Parameters are same in both AFBC and WHRB boilers. The total power generation in our JNILPOWER PLANT is 15.5 MW/H.

Specifications of Turbo-Generators:-

TG#1 = 4 MWWorking Pressure = 35 kg/cm

2

Temperature = 440` C


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Only TG#1 is running in Solo mode.

TG#2 = 4 MWWorking Pressure = 35 kg/cm

2


TG# 2 is running in Grid mode = 132 KV

TG#3 = 7.5 MWWorking Pressure = 35.5 kg/cm

2


B. COKE OVEN POWER PLANT:-In COKE OVEN POWER PLANT we generate 12 MW/H having two WHRB boilers of

21.8 TPH.

Specifications of Turbine:-

Model N66.28

Power related 6 MW Inlet pressure - 6.28 Mpa Exhaust pressure - 0.0098 MPa Rated speed - 3000 r/min Inlet temp - 485` C


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C. ABHIJEET INFRASTRUTURE LIMITED:-In ABHIJEET INFRASTRUTRE LIMITED we generate 15 MW per hour having two boilers

one AFBC & WHRB.

1. AFBC BOILER CAPACITY OF 33 TPH.2. WHRB BOILER CAPACITY OF 38 TPH.

Specifications of turbo-generator:-

Working pressure - 62.8 kg/cm2 Temperature - 490`C RPM - 3000

D. CORPORATE ISPAT ALLOY LIMITED:-In CORPORATE ISPAT ALLOY LIMITED we generate 15 MW PER HOUR having onlyone boiler of WHRB type boilers.

WHRB BOILER HAVING CAPACITY OF 55 TPH.

Specification of turbo-generators:-

Working pressure - 62.8 kg/cm2 Temperature - 490`C RPM - 3000

E. MAA USHA URJA LIMITED:-In MAA USHA URJA LIMITED we generate 7.5 MW PER HOUR having only one AFBCboiler of capacity 33 TPH.

Turbine - 33 TPH. T/G working pressure - 64 kg/cm2 Boiler working pressure- 66kg/cm2 Steam temperature - 495`C Turbine RPM - 3000


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CAPACITIES OF POWER PLANT

JNIL P/P - 15.5 MW

AIL - 15 MW

CIAL - 15 MW

MUUL - 7.5 MW

COKE OVEN P/P- 12 MW

DETAILS OF ALL CONNECTED ELECTRICAL EQUIPMENTS

1. CIRCUIT BREAKER.2. RELAY.3. CONTACTOR.4. ISOLATOR.5. LIGHTNING ARRESTER.6. CURRENT TRANSFORMER.7. POTENTIAL TRANSFORMER.

1. CIRCUIT BREAKER A circuit breaker is an automatically operated electrical switch designed to protect an

electrical circuit from damage caused by overload or short circuit. Its basic function is todetect a fault condition and, by interrupting continuity, to immediately discontinue

electrical flow. Unlike a fuse, which operates once and then must be replaced, a circuitbreaker can be reset (either manually or automatically) to resume normal operation.

Circuit breakers are made in varying sizes, from small devices that protect an individualhousehold appliance up to large switchgear designed to protect high voltage circuits

feeding an entire city.


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BASIC OPERATION OF CIRCUIT BREAKER

All circuit breakers have common features in their operation, although details varysubstantially depending on the voltage class, current rating and type of the circuitbreaker.

The circuit breaker must detect a fault condition; in low-voltage circuit breakers this isusually done within the breaker enclosure. Circuit breakers for large currents or high

voltages are usually arranged with pilot devices to sense a fault current and to operate thetrip opening mechanism. The trip solenoid that releases the latch is usually energized by a

separate battery, although some high-voltage circuit breakers are self-contained withcurrent transformers, protection relays, and an internal control power source.

Once a fault is detected, contacts within the circuit breaker must open to interrupt thecircuit; some mechanically-stored energy (using something such as springs or

compressed air) contained within the breaker is used to separate the contacts, although

some of the energy required may be obtained from the fault current itself. Small circuitbreakers may be manually operated; larger units have solenoids to trip the mechanism,and electric motors to restore energy to the springs.

The circuit breaker contacts must carry the load current without excessive heating, andmust also withstand the heat of the arc produced when interrupting (opening) the circuit.

Contacts are made of copper or copper alloys, silver alloys, and other highly conductivematerials. Service life of the contacts is limited by the erosion of contact material due to

arcing while interrupting the current. Miniature and molded case circuit breakers areusually discarded when the contacts have worn, but power circuit breakers and high-

voltage circuit breakers have replaceable contacts. When a current is interrupted, an arc is generated. This arc must be contained, cooled,

and extinguished in a controlled way, so that the gap between the contacts can againwithstand the voltage in the circuit. Different circuit breakers use vacuum, air, insulating

gas, or oil as the medium the arc forms in. Different techniques are used to extinguish thearc including:

1. Lengthening / deflection of the arc2. Intensive cooling (in jet chambers)3. Division into partial arcs4. Zero point quenching (Contacts open at the zero current time crossing of the AC

waveform, effectively breaking no load current at the time of opening. The zero crossingoccurs at twice the line frequency i.e. 100 times per second for 50 Hz and 120 times per

second for 60 Hz AC)5. Connecting capacitors in parallel with contacts in DC circuits Finally, once the fault condition has been cleared, the contacts must again be closed to

restore power to the interrupted circuit.


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TYPES OF CIRCUIT BREAKER

1. Air circuit breaker.2. Vacuum circuit breaker.3. Sf6 circuit breaker.

AIR CIRCUIT BREAKER:

Air circuit breakers may use compressed air to blow out the arc, or alternatively, the contacts arerapidly swung into a small sealed chamber, the escaping of the displaced air thus blowing out thearc.

The arc interruption in oil is due to the generation of hydrogen gas because of thedecomposition of oil. This fact prompted the investigators to study the interruption in air.

No doubt, arc interruption properties of hydrogen are much superior to air, but air has

several advantages as an arc extinguishing medium as compared to oil. They are:

1. Fire risk & maintenance associated with the use of oil are eliminated.2. Arcing product in air are generally completely removed whereas oil deteriorates with

successive breaking operation .Therefore, the expense of regular oil replacement is

avoided.3. Heavy mechanical stresses set up by gas pressure & oil movement are absent.4. Relatively inferior arc extinguishing properties of air may be offset by using various

principles of arc control & operating air at high pressure .

Fig 1.3air circuit breaker


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This is why except for a certain medium range of voltages, air circuit breakers are widelyused for the low voltage circuits as well as the highest transmission voltages. Simple aircircuit breakers which do not incorporate any arc-control devices are used for lowvoltages, below 1kv. The oil C.Bs. are not used for heavy fault currents on low voltages

due to carbonization of oil & unduly rapid current collapse.

These breakers usually have two pairs of contacts per phase. The main pair of contactscarries the current under normal operating conditions & is made of copper. The additional

pair actually becomes the arcing electrode as the circuit breakers is opened & are made ofcarbon because the vaporization & distortion of the contacts due to the heat of the arc are

confined to these contacts &, therefore, the material used for the contacts should be non-

volatile.

The main contacts separate while the arcing pair is still in contact & the arc is, therefore,initiated only when the arcing pair separates.

VACUUM CIRCUIT BREAKER:

Vacuum circuit breakers have minimal arcing (as there is nothing to ionize other than the contactmaterial), so the arc quenches when it is stretched a very small amount (


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Fig 1.4vacuum circuit breaker

In a Townsend type of discharge, in a gas, the mean free path of the particles is small & electrons

get multiplied due to various ionzation processes & an electron avalanche is fprmed.In a vacuumof the order of 1/100000 torr the mean free path is of the order of few metres & thus when the

electrodes are separated by a few mm an electron crosses the gap without any collision.In thisrange of vacuum the breakdown strength is independent of the gas density & depends only on the

gap length & upon the condition of electrode surface.

SULFUR HEXAFLUORIDE CIRCUIT BREAKERS:

Sulfur hexafluoride circuit breakers sometimes stretch the arc using a magnetic field, and thenrely upon the dielectric strength of the sulfur hexafluoride (SF 6) to quench the stretched arc.

A circuit breaker in which the current carrying contacts operate in SulphurHexafluoride or SF6 gas is known as an SF6 Circuit Breaker.

SF6 has excellent insulating property. SF6 has high electro-negativity. That means ithas high affinity of absorbing free electron. Whenever a free electron collides with theSF6 gas molecule, it is absorbed by that gas molecule and forms a negative ion.


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The attachment of electron with SF6 gas molecules may occur in tow different ways,

1)SF6+e=SF6-2) SF6+ e = SF5

-+ F

These negative ions obviously much heavier than a free electron and therefore over allmobility of the charged particle in the SF6 gas is much less as compared othercommon gases. We know that mobility of charged particle is majorly responsible for

conducting current through a gas.

Fig 1.5- SF6 Circuit Breaker

Hence, for heavier and less mobile charged particles in SF6 gas, it acquires very highdielectric strength. Not only the gas has a good dielectric strength but also it has the unique

property of fast recombination after the source energizing the spark is removed. The gas hasalso very good heat transfer property. Due to its low gaseous viscosity (because of less

molecular mobility) SF6 gas can efficiently transfer heat by convection. So due to its high

dielectric strength and high cooling effect SF6 gas is approximately 100 times more effectivearc quenching media than air. Due to these unique properties of this gas SF6 CircuitBreaker is used in complete range of medium voltage and high voltage electricalpower

system.These circuit breakers are available for the voltage ranges from 33KV to 800KV and

even more.


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2. RELAY A relay is an electrically operated switch. Many relays use an electromagnet to

operate a switching mechanism mechanically, but other operating principles are also

used. Relays are used where it is necessary to control a circuit by a low-power signal(with complete electrical isolation between control and controlled circuits), or where

several circuits must be controlled by one signal.

The first relays were used in long distance telegraph circuits, repeating the signalcoming in from one circuit and re-transmitting it to another. Relays were used

extensively in telephone exchanges and early computers to perform logicaloperations.

Fig 1.6 - RELAY
http://en.wikipedia.org/wiki/File:Relay_Parts.jpg


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BASIC OPERATION OF RELAY:

A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core,an iron yoke which provides a low reluctance path for magnetic flux, a movable iron

armature, and one or more sets of contacts (there are two in the relay pictured).

The armature is hinged to the yoke and mechanically linked to one or more sets ofmoving contacts. It is held in place by a spring so that when the relay is de-energized

there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts

in the relay pictured is closed, and the other set is open. Other relays may have more or

fewer sets of contacts depending on their function.

The relay in the picture also has a wire connecting the armature to the yoke. This ensurescontinuity of the circuit between the moving contacts on the armature, and the circuittrack on the printed circuit board (PCB) via the yoke, which is soldered to the PCB.

When an electric current is passed through the coil it generates a magnetic field thatactivates the armature and the consequent movement of the movable contact either makes

or breaks (depending upon construction) a connection with a fixed contact. If the set of

contacts was closed when the relay was de-energized, then the movement opens the

contacts and breaks the connection, and vice versa if the contacts were open.

When the current to the coil is switched off, the armature is returned by a force,approximately half as strong as the magnetic force, to its relaxed position. Usually this

force is provided by a spring, but gravity is also used commonly in industrial motor

starters. Most relays are manufactured to operate quickly. In a low-voltage application

this reduces noise; in a high voltage or current application it reduces arcing.

When the coil is energized with direct current, a diode is often placed across the coil todissipate the energy from the collapsing magnetic field at deactivation, which would

otherwise generate a voltage spike dangerous to semiconductor circuit components. Some

automotive relays include a diode inside the relay case.

Alternatively, a contact protection network consisting of a capacitor and resistor in series(snubber circuit) may absorb the surge. If the coil is designed to be energized with

alternating current (AC), a small copper "shading ring" can be crimped to the end of the

solenoid, creating a small out-of-phase current which increases the minimum pull on thearmature during the AC cycle.


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TYPE OF RELAYS:-

Over voltage relay Field failure relay Earth fault relay. Reverse fault relay. Low forward relay. Buchholz relay.

3. ISOLATOR In electrical engineering, a disconnected or isolator switch or disconnect switch is

used to make sure that an electrical circuit can be completely de-energized for service

or maintenance. Such switches are often found in electrical distribution and industrialapplications where machinery must have its source of driving power removed for

adjustment or repair.

High-voltage isolation switches are used in electrical substations to allow isolation ofapparatus such as circuit breakers and transformers, and transmission lines, for

maintenance. Often the isolation switch is not intended for normal control of thecircuit and is used only for isolation; in such a case, it functions as a second, usually

physically distant master switch (wired in series with the primary one) that canindependently disable the circuit even if the master switch used in everyday operation

is turned on.

Isolator switches have provisions for a padlock so that inadvertent operation is notpossible. In high voltage or complex systems, these padlocks may be part of a

trapped-key interlock system to ensure proper sequence of operation.

In some designs the isolator switch has the additional ability to earth the isolatedcircuit thereby providing additional safety. Such an arrangement would apply to

circuits which inter-connect power distribution systems where both end of the circuitneed to be isolated.

The major difference between an isolator and a circuit breaker is that an isolator is anoff-load device intended to be opened only after current has been interrupted by someother control device. Safety regulations of the utility must prevent any attempt to

open the disconnected while it supplies a circuit.

Standards in some countries for safety may require either local motor isolators orlockable overloads (which can be padlocked).


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4.CONTACTOR:-

Contactor is an electrically controlled switch used for switching a power circuit, similarto a relay except with higher current ratings. A contactor is controlled by a circuit which

has a much lower power level than the switched circuit.

Fig 1.7: CONTACTOR

Contactors come in many forms with varying capacities and features. Unlike a circuitbreaker, a contractor is not intended to interrupt a short circuit current. Contactors rangefrom those having a breaking current of several amperes to thousands of amperes and 24

V DC to many kilovolts. The physical size of contactors ranges from a device smallenough to pick up with one hand, to large devices approximately a meter (yard) on a side.

Contactors are used to control electric motors, lighting, heating, capacitor banks, andother electrical loads.


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LIGHTENING ARRESTOR:-

A lightning arrester is a device used on electrical power systems and telecommunicationssystems to protect the insulation and conductors of the system from the damaging effects

of lightning. The typical lightning arrester has a high-voltage terminal and a ground

terminal. When a lightning surge (or switching surge, which is very similar) travels along the

power line to the arrester, the current from the surge is diverted through the arrestor, inmost cases to earth.

o Fig 1.8: LIGHTENING ARRESTOR In telegraphy and telephony, a lightning arrestor is placed where wires enter a

structure, preventing damage to electronic instruments within and ensuring the

safety of individuals near them. Smaller versions of lightning arresters, also called surge protectors, are devices

that are connected between each electrical conductor in power and

communications systems and the Earth. These prevent the flow of the normal

power or signal currents to ground, but provide a path over which high-voltage

lightning current flows, bypassing the connected equipment. Their purpose is to

limit the rise in voltage when a communications or power line is struck by

lightning or is near to a lightning strike.

If protection fails or is absent, lightning that strikes the electrical systemintroduces thousands of kilovolts that may damage the transmission lines, and can

also cause severe damage to transformers and other electrical or electronicdevices. Lightning-produced extreme voltage spikes in incoming power lines can

damage electrical home appliances.


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4.CURRENT TRANSFORMERS:-

Fig1.9 . Current transformers used in metering equipment forthree-phase 400 ampere electricity

supply

A current transformer (CT) is a measurement device designed to provide a current in itssecondary coil proportional to the current flowing in its primary. Current transformers are

commonly used in metering and protective relays in theelectrical power industry wherethey allow safe measurement of large currents, often in the presence ofhigh voltages.The

current transformer safely isolates measurement and control circuitry from the highvoltages typically present on the circuit being measured.

Current transformers are often constructed by passing a single primary turn (either aninsulated cable or an un-insulated bus bar) through a well-insulatedtoroidal core wrappedwith many turns of wire. The CT is typically described by its current ratio from primary

to secondary. For example, a 4000:5 CT would provide an output current of 5 ampereswhen the primary was passing 4000 amperes.

The secondary winding can be single ratio or have severaltappoints to provide a range ofratios. Care must be taken that the secondary winding is not disconnected from its load

while current flows in the primary, as this will produce a dangerously high voltage acrossthe open secondary and may permanently affect the accuracy of the transformer.

Specially constructed wideband CTs are also used, usually with an oscilloscope, tomeasurehigh frequencywaveforms or pulsed currents withinpulsed power systems. Onetype provides a voltage output that is proportional to the measured current; another,

called a Rogowski coil,requires an external integrator in order to provide a proportionaloutput.
http://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Electrical_power_industryhttp://en.wikipedia.org/wiki/High_voltagehttp://en.wikipedia.org/wiki/Electrical_insulationhttp://en.wikipedia.org/wiki/Torushttp://en.wikipedia.org/wiki/Tap_(transformer)http://en.wikipedia.org/wiki/Widebandhttp://en.wikipedia.org/wiki/Oscilloscopehttp://en.wikipedia.org/wiki/High_frequencyhttp://en.wikipedia.org/wiki/Waveformhttp://en.wikipedia.org/wiki/Pulsed_powerhttp://en.wikipedia.org/wiki/Rogowski_coilhttp://en.wikipedia.org/wiki/Integratorhttp://en.wikipedia.org/wiki/File:CurrentTransformers.jpghttp://en.wikipedia.org/wiki/Integratorhttp://en.wikipedia.org/wiki/Rogowski_coilhttp://en.wikipedia.org/wiki/Pulsed_powerhttp://en.wikipedia.org/wiki/Waveformhttp://en.wikipedia.org/wiki/High_frequencyhttp://en.wikipedia.org/wiki/Oscilloscopehttp://en.wikipedia.org/wiki/Widebandhttp://en.wikipedia.org/wiki/Tap_(transformer)http://en.wikipedia.org/wiki/Torushttp://en.wikipedia.org/wiki/Electrical_insulationhttp://en.wikipedia.org/wiki/High_voltagehttp://en.wikipedia.org/wiki/Electrical_power_industryhttp://en.wikipedia.org/wiki/Three-phase


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CONSTRUCTION OF CURRENT TRANSFORMER:

Fig 1.10- CONSTRUCTION OF CURRENT TRANSFORMER

Like any othertransformer,a current transformer has a primary winding, amagneticcore, and a secondary winding. The alternating current flowing in the primary

produces a magnetic field in the core, which then induces a current in the secondarywinding circuit. A primary objective of current transformer design is to ensure that

the primary and secondary circuits are efficiently coupled, so that the secondary

current bears an accurate relationship to the primary current.

The most common design of CT consists of a length of wire wrapped many timesaround a silicon steel ring passed over the circuit being measured. The CT's primarycircuit therefore consists of a single 'turn' of conductor, with a secondary of many tens

or hundreds of turns.

The primary winding may be a permanent part of the current transformer, with aheavy copper bar to carry current through the magnetic core. Window-type current

transformers (aka zero sequence current transformers, or ZSCT) are also common,which can have circuit cables run through the middle of an opening in the core to

provide a single-turn primary winding. When conductors passing through a CT arenot centered in the circular (or oval) opening, slight inaccuracies may occur.
http://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Magnetic_corehttp://en.wikipedia.org/wiki/Magnetic_corehttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/File:SF6_current_transformer_TGFM-110_Russia.jpghttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Magnetic_corehttp://en.wikipedia.org/wiki/Magnetic_corehttp://en.wikipedia.org/wiki/Magnetic_corehttp://en.wikipedia.org/wiki/Transformer


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6. POTENTIAL TRANSFORMERS

Voltage transformers (VT) or potential transformers (PT) are another type ofinstrument transformer, used for metering and protection in high-voltage circuits.

They are designed to present negligible load to the supply being measured and to

have a precise voltage ratio to accurately step down high voltages so that metering

and protective relay equipment can be operated at a lower potential. Typically the

secondary of a voltage transformer is rated for 69 V or 120 V at rated primary

voltage, to match the input ratings of protective relays.

The transformer winding high-voltage connection points are typically labeled as H1,H2(sometimes H0if it is internally grounded) and X1, X2 and sometimes an X3 tap

may be present. Sometimes a second isolated winding (Y1, Y2, Y3) may also be

available on the same voltage transformer. The high side (primary) may be connected

phase to ground or phase to phase. The low side (secondary) is usually phase to

ground. The terminal identifications (H1, X1, Y1, etc.) are often referred to as polarity. This

applies to current transformers as well. At any instant terminals with the same suffix

numeral have the same polarity and phase. Correct identification of terminals and

wiring is essential for proper operation of metering and protective relays.

Some meters operate directly on the secondary service voltages at or below 600 V.VTs are typically used for higher voltages (for example, 765 kV for power

transmission), or where isolation is desired between the meter and the measured

circuit.

There are primarily three types of voltage transformers (VT):-

1. Electromagnetic voltage transformer.2. Capacitor voltage transformer.3. Optical voltage transformer. The electromagnetic voltage transformer is a wire-wound transformer. The capacitor voltage transformer uses a capacitance potential divider and is

primarily used at higher voltages due to a lower cost than an electromagnetic VT.

An optical voltage transformer exploits the electrical properties of opticalmaterials.
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MAJOR MOTOR DATA

JNIL POWER PLANT

P.A FAN - 45KW

F.D FAN 160 KW

ID FAN - 75KW

CRUSHER - 45 KW

WATER PUMP - 110 KW

(T.G -1 ,T.G-2 ,T.G.-3) - 2.2 KW

PUMP HOUSE # 3

GROUP 3(5 MOTORS) - 265 KW

GROUP1(3 MOTORS) - 270 KW

GROUP 2(2 MOTORS) - 197 KW

1 EXTERNAL MOTOR - 350 KW

COOLING TOWER # 2 (FOR JNIL POWER PLANT)

CT FAN 1 - 37 KW

CT FAN 2 -37 KW

CT FAN 3 -37 KW

CT FAN 4 -37 KW


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CIAL POWER PLANT

EOP 75 kw *2

RCW PUMP - 132 KW *3

CT.CEP - 22 KW*2(cooling tower)

CT. FAN 22KW * 3

CEP - 45 KW *2

RSB - 0.18 KW*7

LRSB - 1.1 KW *3

SBOP - 11KW (STANDBY OIL PUMP)

SOP - 110 KW (STARTING OIL PUMP)

JOP - 150 KW (JACKINH OIL PUMP)

TURNING GEAR - 5.5 KW

ROOT BLOWER I -7.5 KW

ROOT BLOWER II - 5.5 KW


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MAA USHA POWER PLANT

BOILER FEED PUMP - 160 KW

FD FAN - 90 KW *2

ID FAN - 30 KW *2

PA FAN - 45 KW *1

CEP 30 KW

CT. FAN - 22 KW *2

ACW PUMP - 22 KW *2

RCW PUMP - 37 KW *2

COAL CRUSHER 45 KW

ASH COMPRESSOR - 75 KW

NOTEHERE abbreviations ARE:-

BFP - BOILER FEED PUMP

RCW - RECIRCULATING WATER PUMP

ACW AUXILLARY CIRCULATING PUMP

PA FAN- PRIMARY AIR FAN

ID FANINDUSED DRAFT FAN

FD FANFORCED DRAFT FAN

CEW - CONDENSATE EXTRACTED PUMP

C.T FAN - COOLING TOWER FAN

EOP - EMERGENCY OIL PUMP

CT COOLING TOWER


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ESP (ELECTROSTATIC PRECIPITATOR)

An electrostatic precipitator is a large, industrial emission-control unit. It is designed to trap andremove dust particles from the exhaust gas stream of an industrial process. Precipitators are used

in these industries:-

Power/Electric Cement Chemicals Metals PaperIn industrial plants, particulate matter created in the industrial process is carried as dust in the hotexhaust gases. These dust-laden gases pass through an electrostatic precipitator that collects most

of the dust. Cleaned gas then passes out of the precipitator and through a stack to the atmosphere.

Precipitators typically collect 99.9% or more of the dust from the gas stream.Precipitators function by electrostatically charging the dust particles in the gas stream. Thecharged particles are then attracted to and deposited on plates or other collection devices. When

enough dust has accumulated, the collectors are shaken to dislodge the dust, causing it to fallwith the force of gravity to hoppers below. The dust is then removed by a conveyor system for

disposal or recycling of dust.Depending upon dust characteristics and the gas volume to be treated, there are many different

sizes, types and designs of electrostatic precipitators.


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BASIC PRINCIPLES:-

Electrostatic precipitation removes particles from the exhaust gas stream of an industrial process.Often the process involves combustion, but it can be any industrial process that would otherwise

emit particles to the atmosphere.Six activities typically take place:

Ionization - Charging of particlesMigration - Transporting the charged particles to the collecting surfaces

Collection - Precipitation of the charged particles onto the collecting surfacesCharge Dissipation - Neutralizing the charged particles on the collecting surfaces

Particle Dislodging - Removing the particles from the collecting surface to the hopper

Particle Removal - Conveying the particles from the hopper to a disposal point

The major precipitator components that accomplish these activities are as follows:

Discharge ElectrodesCollecting Electrodes

Rapping SystemsElectric Power Supply


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DISCHARGE ELECTRODES:-

Discharge electrodes emit charging current and provide voltage that generates an electrical field

between the discharge electrodes and the collecting plates. The electrical field forces dust

particles in the gas stream to migrate toward the collecting plates. The particles then precipitateonto the collecting plates.

Discharge electrodes are typically supported from the upper discharge frame and are held inalignment between the upper and lower discharge frames. The upper discharge frame is in turnsupported from the roof of the precipitator casing.The discharge electrodes are shown in the

above Figure.

COLLECTING PLATES:-

Collecting plates are designed to receive and retain the precipitated particles until they areintentionally removed into the hopper. Collecting plates are also part of the electrical power

circuit of the precipitator.Collecting plates are suspended from the precipitator casing and form the gas passages within the

precipitator.


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While the design of the collecting plates varies by manufacturer, there are two commondesigns:

Plates supported from anvil beams at either end The anvil beam is also the point of impact forthe collecting rapper. Plates supported with hooks directly from the precipitator casing

Two or more collecting plates are connected at or near the center by rapper beams, which thenserve as impact points for the rapping system

ELECRTIC POWER SUPPLY :-

The power supply system is designed to provide voltage to the electrical field (or bus section) at

the highest possible level. The voltage must be controlled to avoid causing sustained arcing orsparking between the electrodes and the collecting plates.

Electrically, a precipitator is divided into a grid, with electrical fields in series (in the direction ofthe gas flow) and one or more bus sections in parallel (cross-wise to the gas flow). When

electrical fields are in series, the power supply for each field can be adjusted to optimizeoperation of that field. Likewise, having more than one electrical bus section in parallel allows

adjustments to compensate for their differences, so that power input can be optimized. The

power supply system has four basic components:

Automatic voltage control Step-up transformer High-voltage rectifier Voltage controlThe ideal automatic voltage control would produce the maximum collecting efficiency by

holding the operating voltage of the precipitator at a level just below the spark-over voltage.However, this level cannot be achieved given that conditions change from moment to moment.

TRANSFORMER-RECTIFIERS

The transformer-rectifier rating should be matched to the load imposed by the electrical field orbus section. The power supply will perform best when the transformer-rectifiers operate at 70 -

90% of the rated capacity, without excessive sparking. This reduces the maximum continuous-load voltage and corona power inputs.


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RAPPING SYSTEM :-

Rappers are time-controlled systems provided for removing dust from the collecting plates andthe discharge electrodes as well as for gas distribution devices (optional) and for hopper walls

(optional). Rapping systems may be actuated by electrical or pneumatic power, or by mechanical

means. Tumbling hammers may also be used to dislodge ash. Rapping methods include:-

Electric vibrators Electric solenoid piston drop rappers Tumbling hammers

In general, discharge electrodes should be kept as free as possible of accumulated particulate.

The rapping system for the discharge electrodes should be operated on a continuous schedulewith repeat times in the 2 - 4 minute range, depending on the size and inlet particulate loading of

the precipitator.

The first electrical field generally collects about 60-80% of the inlet dust load. The first fieldplates should be rapped often enough so that their precipitated layer of particulate is about 3/8 -1/2" thick. There is no advantage in rapping more often since the precipitated dust has not yet

agglomerated to a sheet which requires a minimum layer thickness. Sheet formation is essentialto make the dust drop into the precipitator hopper without re-entrainment into the gas stream.

Rapping less frequently typically results in a deterioration of the electrical power input by addingan additional resistance into the power circuit.

The only rapping system requiring optimization is the collecting plate rapping system. The

optimization should start with the Collecting Plate Rapping Schedule determined above. Next,the rapping frequency of the inlet field should be increased or decreased until the electrical

power input of the inlet field remains constant. Next, the rapping frequency of the other fieldsshould be adjusted in sequence until their electrical power inputs remain constant. If the stack

opacity trace shows rapping spikes, the rapping intensity should be reduced while observing theelectrical power input of the precipitator.

The adjustment of the rapping system for optimum precipitator performance is a slow process. Itrequires a substantial amount of time for stabilization after each adjustment.


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EXCITER

The exciter is the "backbone" of the generator control system. It is the power source that suppliesthe dc magnetizing current to the field windings of a

synchronous generator thereby ultimately inducing ac voltage and current in the generator

armature.Two basic kinds of excitors are:-

Rotating (Brush and brushless) Static exciters (Shunt and series)

ROTATING EXCITERS

Brushless: do not require slip-rings, commutators, brushes and are practically maintenance free.

Brush Type: require slip-rings, commutators and brushes and require periodic maintenance

STATIC EXCITERS

Static excitation means no moving parts. It provides faster transient response than rotary excitersShunt Type: operating field power from generator output voltage

Series Type: operating field power from generator output voltage & current

ALTERNATE VOLTAGE REGULATOR

AVR is designed to automatically maintain a constantvoltage level. A voltage regulator may bea simple "feed-forward" design or may includenegative feedbackcontrol loops.It may use an

electromechanicalmechanism,or electronic components. Depending on the design, it may beused to regulate one or moreAC orDC voltages.
http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Negative_feedbackhttp://en.wikipedia.org/wiki/Control_theoryhttp://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Mechanism_(technology)http://en.wikipedia.org/wiki/Control_theoryhttp://en.wikipedia.org/wiki/Negative_feedbackhttp://en.wikipedia.org/wiki/Voltage


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GENERATOR

Equipment that convertsmechanicalenergy into electrical energy.

Essentially, there are two basic types of generators:

DC generators AC generators Asynchronous (Induction) generators Synchronous generators

INDUCTION GENERATORS

The induction generator is nothing more than an induction motor driven above its synchronousspeed by an amount not exceeding the full load slip the unit would have as a motor.

Assuming a full load slip of 3%, a motor with a synchronous speed of 1200 rpm would have afull load speed of 1164 rpm. This unit could also be driven by an external prime mover at 1236

rpm for use as an induction generator.

SYNCHRONOUS GENERATORS

Synchronous generators are used because they offer precise control of voltage, frequency, VARsand WATTs. This control is achieved through the use of voltage regulators and governors.

A synchronous machine consists of a stationary armature winding (stator) with many wiresconnected in series or parallel to obtain the desired terminal voltage. The armature winding is

placed into a slotted laminated steel core. A synchronous machine also consists of a revolving

DC field - the rotor
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INSTRUMENTATION


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SPECIFICATION (JNIL/POWER PLANT)

In JNIL, for 1 boiler, 9 control valves, 11 power cylinder, 13 actuators,15 solenoidvalves,20 limit switches & 9 pressure switches are used. For measuring temperature, J &K type thermocouple are used as a temperature element & RTD (PT 100) are used.

In AIL power plant, 1 WHRB boiler is used. In these boiler 3 types of control valves usedwhich are followings-

Temperature control valve Feed water control valve Shoot blower control valve

In boilers, k type thermocouple are used & totally there are 18 control valves & 2 shutoffvalves in AIL.

In CIAL, flue gas attemprator control valve is used as temperature control valve & shootblower is used for controlling air. Shoot blower is used at steam drum side.In WHRB

boiler,1 pressure transmitter & 3 level transmitter are used which checks the level of

drum & pressure in drum.

In flue gas inlet, 1 temperature transmitter & 1 pressure transmitter are used. In steam, aflow transmitter is also used.2 indicator used in boiler which is steam drum level

indicator & temperature indicator.

THERMOCOUPLE

A thermocoupleconsists of two conductors of different materials (usually metal alloys)that produce a voltage in the vicinity of the point where the two conductors are in contact.The voltage produced is dependent on, but not necessarily proportional to, the difference

of temperature of the junction to other parts of those conducttrrs. Thermocouples are awidely used type of temperature sensor for measurement and control and can also be used

to convert a temperature gradient into electricity.

Commercial thermocouples are inexpensive, interchangeable, are supplied with standardconnectors, and can measure a wide range of temperatures. In contrast to most othermethods of temperature measurement, thermocouples are self powered and require no

external form of excitation. The main limitation with thermocouples is accuracy; systemerrors of less than one degree Celsius (C) can be difficult to achieve.


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PRINCIPLE OF OPERATION

In 1821, the GermanEstonian physicist Thomas Johann Seebeck discovered that when any

conductor is subjected to a thermal gradient, it will generate a voltage. This is now known as thethermoelectric effect or Seebeck effect. Any attempt to measure this voltage necessarily involves

connecting another conductor to the "hot" end. This additional conductor will then alsoexperience the temperature gradient, and develop a voltage of its own which will oppose the

original.

Fortunately, the magnitude of the effect depends on the metal in use. Using a dissimilar metal tocomplete the circuit creates a circuit in which the two legs generate different voltages, leaving a

small difference in voltage available for measurement. That difference increases withtemperature, and is between 1 and 70 microvolts per degree Celsius (V/C) for standard metal

combinations.
http://en.wikipedia.org/wiki/File:Thermocouple_circuit.svg


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The voltage is not generated at the junction of the two metals of the thermocouple but rather

along that portion of the length of the two dissimilar metals that is subjected to atemperature

gradient. Because both lengths of dissimilar metals experience the same temperature

gradient, the end result is a measurement of the difference in temperature between the

thermocouple junction and the reference Types

TYPES OF THERMOCOUPLES

K -THERMOCOUPLE

Type K (chromel {90% nickel and 10% chromium}alumel {95% nickel, 2% manganese, 2%

aluminium and 1% silicon}) is the most common general purpose thermocouple with a

sensitivity of approximately 41 V/C, chromel positive relative to alumel.[9] It is inexpensive,and a wide variety of probes are available in its 200 C to +1250 C / -330 F to +2460 F

range. .Wire color standard is yellow (+) and red (-).

E- THERMOCOUPLE

Type E (chromelconstantan)[6]

has a high output (68 V/C) which makes it well suited to

cryogenic use. Additionally, it is non-magnetic. Wide range is -50 to 740 C and Narrow range is

-110 to 140 C. Wire color standard is purple (+) and red (-).

J -THERMOCOUPLE

Type J (ironconstantan) has a more restricted range than type K (40 to +750 C), but higher

sensitivity of about 55 V/C.]The Curie point of the iron (770 C)

]causes an abrupt change in

the characteristic, which determines the upper temperature limit.

PLATINUM TYPES B, R, AND S THERMOCOUPLE

Types B, R, and S thermocouples use platinum or a platinumrhodium alloy for each conductor.

These are among the most stable thermocouples, but have lower sensitivity than other types,approximately 10 V/C. Type B, R, and S thermocouples are usually used only for high

temperature measurements due to their high cost and low sensitivity.

B -THERMOCOUPLE

Type B thermocouples use a platinumrhodium alloy for each conductor. One conductor

contains 30% rhodium while the other conductor contains 6% rhodium. These thermocouples aresuited for use at up to 1800 C. Type B thermocouples produce the same output at 0 C and 42

C, limiting their use below about 50 C.
http://en.wikipedia.org/wiki/Chromelhttp://en.wikipedia.org/wiki/Alumelhttp://en.wikipedia.org/wiki/Thermocouple#cite_note-MNL_12-9http://en.wikipedia.org/wiki/Thermocouple#cite_note-MNL_12-9http://en.wikipedia.org/wiki/Thermocouple#cite_note-MNL_12-9http://en.wikipedia.org/wiki/Thermocouple#cite_note-Baker2000-6http://en.wikipedia.org/wiki/Thermocouple#cite_note-Baker2000-6http://en.wikipedia.org/wiki/Thermocouple#cite_note-Baker2000-6http://en.wikipedia.org/wiki/Thermocouple#cite_note-Baker2000-6http://en.wikipedia.org/wiki/Thermocouple#cite_note-MNL_12-9http://en.wikipedia.org/wiki/Alumelhttp://en.wikipedia.org/wiki/Chromel


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R- THERMOCOUPLE

Type R thermocouples use a platinumrhodium alloy containing 13% rhodium for one conductorand pure platinum for the other conductor. Type R thermocouples are used up to 1600 C.

S -THERMOCOUPLE

Type S thermocouples are constructed using one wire of 90% Platinum and 10% Rhodium (thepositive or "+" wire) and a second wire of 100% platinum (the negative or "-" wire). Like type R,

type S thermocouples are used up to 1600 C. In particular, type S is used as the standard ofcalibration for the melting point of gold (1064.43 C).

T -THERMOCOUPLE

Type T (copperconstantan) thermocouples are suited for measurements in the 200 to 350 C

range. Often used as a differential measurement since only copper wire touches the probes. Since

both conductors are non-magnetic, there is no Curie point and thus no abrupt change incharacteristics. Type T thermocouples have a sensitivity of about 43 V/C.

C- THERMOCOUPLE

Type C (tungsten 5% rhenium tungsten 26% rhenium) thermocouples are suited for

measurements in the 0 C to 2320 C range. This thermocouple is well-suited for vacuumfurnaces at extremely high temperatures. It must never be used in the presence of oxygen at

temperatures above 260 C.

M- THERMOCOUPLE

Type M thermocouples use a nickel alloy for each wire. The positive wire (20 Alloy) contains18% molybdenum while the negative wire (19 Alloy) contains 0.8% cobalt. These

thermocouples are used in vacuum furnaces for the same reasons as with type C. Uppertemperature is limited to 1400 C. It is less commonly used than other types.

CHROMEL-GOLD/IRON THERMOCOUPLE

In chromel-gold/iron thermocouples, the positive wire is chromel and the negative wire is gold

with a small fraction (0.030.15 atom percent) of iron. It can be used for cryogenic applications

(1.2300 K and even up to 600 K). Both the sensitivity and the temperature range depends on theiron concentration. The sensitivity is typically around 15 V/K at low temperatures and the

lowest usable temperature varies between 1.2 and 4.2 K.


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RTD (RESISTANCE TEMPERATURE DETECTORS)

Resistance thermometers, also called resistance temperature detectors (RTDs), are sensorsused to measure temperature by correlating the resistance of the RTD element with temperature.

Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass

core. The element is usually quite fragile, so it is often placed inside a sheathed probe to protectit.

The RTD element is made from a pure material, platinum, nickel or copper. The material has apredictable change in resistance as the temperature changes; it is this predictable change that is

used to determine temperature. They are slowly replacing the use of thermocouples in manyindustrial applications below 600 C, due to higher accuracy and repeatability.

FUNCTION

Resistance thermometers are constructed in a number of forms and offer greater stability,

accuracy and repeatability in some cases than thermocouples. While thermocouples use theSeebeck effect to generate a voltage, resistance thermometers use electrical resistance and

require a power source to operate. The resistance ideally varies linearly with temperature.

The platinum detecting wire needs to be kept free of contamination to remain stable. A platinumwire or film is supported on a former in such a way that it gets minimal differential expansion or

other strains from its former, yet is reasonably resistant to vibration. RTD assemblies made fromiron or copper are also used in some applications. Commercial platinum grades are produced

which exhibit a temperature coefficient of resistance 0.00385/C (0.385%/C) (EuropeanFundamental Interval). The sensor is usually made to have a resistance of 100 at 0 C.

Measurement of resistance requires a small current to be passed through the device under test.This can cause resistive heating, causing significant loss of accuracy if manufacturers' limits arenot respected, or the design does not properly consider the heat path. Mechanical strain on the

resistance thermometer can also cause inaccuracy.

Lead wire resistance can also be a factor; adopting three- and four-wire, instead of two-wire,

connections can eliminate connection lead resistance effects from measurements .three-wireconnection is sufficient for most purposes and almost universal industrial practice. Four-wire

connections are used for the most precise applications.

ADVANTAGES AND LIMITATIONS

The advantages of platinum resistance thermometers include:

High accuracy Low drift Wide operating range Suitability for precision applications.


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LIMITATIONS:

RTDs in industrial applications are rarely used above 660 C. At temperatures above 660 C it

becomes increasingly difficult to prevent the platinum from becoming contaminated byimpurities from the metal sheath of the thermometer. This is why laboratory standard

thermometers replace the metal sheath with a glass construction. At very low temperatures, saybelow -270 C (or 3 K), because there are very few phonons, the resistance of an RTD is mainly

determined by impurities and boundary scattering and thus basically independent of temperature.As a result, the sensitivity of the RTD is essentially zero and therefore not useful.

Compared to thermistors, platinum RTDs are less sensitive to small temperature changes andhave a slower response time. However, thermistors have a smaller temperature range and

stability.

WIRING CONFIGURATIONS

two-wire configuration

The simplest resistance thermometer configuration uses two wires. It is only used when highaccuracy is not required, as the resistance of the connecting wires is added to that of the sensor,

leading to errors of measurement. This configuration allows use of 100 meters of cable. Thisapplies equally to balanced bridge and fixed bridge system.
http://en.wikipedia.org/wiki/File:Twowire.gif


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three-wire configuration

In order to minimize the effects of the lead resistances, a three-wire configuration can be used.Using this method the two leads to the sensor are on adjoining arms. There is a lead resistance in

each arm of the bridge so that the resistance is cancelled out, so long as the two lead resistancesare accurately the same. This configuration allows up to 600 meters of cable.

four-wire configuration

The four-wire resistance thermometer configuration increases the accuracy and reliability of theresistance being measured: the resistance error due to lead wire resistance is zero. In the diagram

above a standard two-terminal RTD is used with another pair of wires to form an additional loopthat cancels out the lead resistance. The above Wheatstone bridge method uses a little more

copper wire and is not a perfect solution. Below is a better configuration, four-wire Kelvinconnection. It provides full cancellation of spurious effects; cable resistance of up to 15 can be

handled.
http://en.wikipedia.org/wiki/File:4wirebetter.gifhttp://en.wikipedia.org/wiki/File:Fourwire.gifhttp://en.wikipedia.org/wiki/File:Threewire.gif


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CONTROL VALVES

Control valves are valves used to control conditions such as flow, pressure, temperature, and

liquid level by fully or partially opening or closing in response to signals received fromcontrollers that compare a "set point" to a "process variable" whose value is provided by sensorsthat monitor changes in such conditions.

The opening or closing of control valves is usually done automatically by electrical, hydraulic orpneumatic actuators. Positioners are used to control the opening or closing of the actuator based

on electric, or pneumatic signals. These control signals, traditionally based on 3-15psi (0.2-1.0bar), more common now are 4-20mA signals for industry, 0-10V for HVAC systems, and the

introduction of "Smart" systems, HART, Fieldbus Foundation, and Profibus being the morecommon protocols.

Control valves come in two sorts: air to open; and air to close. Air to open valves are normallyheld closed by the spring and require air pressure (a control signal) to open them - they openprogressively as the air pressure increases. Air to close valves are valves which are held open by

the valve spring and require air pressure to move them towards the closed position. The reasonfor the two types of valves is to allow failsafe operation.

In the event of a plant instrument air failure it is important that all control valves fail in a safe

position (e.g. an exothermic reactor's feed valves (or, perhaps, just one of the valves) should failclosed (air to open) and its coolant system valves fail open (air to close)). The type of valve used

obviously impacts on what a controller has to do - changing the type of valve would mean thatthe controller would need to move the manipulation in the opposite direction.

TEMPERATURE TRANSMITTER

A temperature transmitter works by connecting to it some form of temperature sensor. Forexample a RTD (Resistance temperature device) or Thermocouple. In the case of a RTDconnected to the transmitter the transmitter measures a change in resistance of the RTD

proportional to the change in temperature measured. The transmitter then derives a current output(generally 4-20mA) which can be measured by an instrument, such as a PLC, loop indicator etc.

In the case of a thermocouple a milli voltage is produced at a junction of two dissimilar metals,

this change in milli voltage again proportional to the change in temperature and the transmitteragain derives a current output measurable by a instrument.

The transmitter will be ranged by a programming device, say for example an application whereprocess temperatures need to be measured between 0-100 degrees, the transmitter will be ranged

0-100 degrees and thus give an output proportional to the temperature measured by the sensingelement. 0 degrees = 4mA, 100 degrees = 20mA.


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A excitation supply will be connected to the transmitter and the 4-20mA will flow in this loop

back to the measuring instrument.It is necessary to use the correct type of sensor for theapplication to get the best accuracy when measuring. RTD's are generally used for measuring

lower temperatures where as thermocouples are used for measuring higher temperatures.

There are several types of RTD's such as 2 wire, 3 wire and 4 wire and an even greater range ofthermocouples depending on the temperatures and measuring environment.

PRESSURE TRANSMITTER

A pressure transmitter is a pressure sensor with a signal processing circuit so the pressure is transmitted

as an electrical analogue of the pressure. This might be a 4-20mA current loop signal, where the current

in mA is related to the pressure. Zero pressure would be 4mA, and fullscale would be 20mA. Loop up 4-

20mA current loop for more info. Some may have other outputs such as serial data digital outputs

(RS232 signal), while others could have an analogue voltage, perhaps 0-10V.

The typical pressure sensor uses a diaphragm to convert pressure (units of force per unit area) to a

force, which moves the diaphragm against a restoring force such as a spring, bellows or even electrically

controlled force balance. The movement or the balancing force is measured as strain or displacement.

The strain or displacement signal is proportional to pressure, and additional signal processing converts

the signal to an electrical equivalent of pressure units that are transmitted by the analogue output.

Usually the diaphragm has a reference pressure on one side, so it actually measures the difference in

pressure. This can be the atmosphere for gauge sensors, a vacuum for absolute sensors, or a second

pressure port for differential sensors

FLOW METERS

Measuring the flow of liquids is a critical need in many industrial plants. In some operations, theability to conduct accurate flow measurements is so important that it can make the difference

between making a profit or taking a loss. In other cases, inaccurate flow measurements or failureto take measurements can cause serious (or even disastrous) results.

With most liquid flow measurement instruments, the flow rate is determined inferentially bymeasuring the liquid's velocity or the change in kinetic energy. Velocity depends on the pressure

differential that is forcing the liquid through a pipe or conduit. Because the pipe's cross-sectionalarea is known and remains constant, the average velocity is an indication of the flow rate.


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The basic relationship for determining the liquid's flow rate in such cases is:

Q = V x A

where

Q = liquid flow through the pipe

V = average velocity of the flow

A = cross-sectional area of the pipe

Other factors that affect liquid flow rate include the liquid's viscosity and density, and the

friction of the liquid in contact with the pipe.

Direct measurements of liquid flows can be made with positive-displacement flowmeters. Theseunits divide the liquid into specific increments and move it on. The total flow is an accumulation

of the measured increments, which can be counted by mechanical or electronic techniques.

DIFFERENTIAL PRESSURE METERS

The use of differential pressure as an inferred measurement of a liquid's rate of flow is well

known. Differential pressure flow meters are, by far, the most common units in use today.Estimates are that over 50 percent of all liquid flow measurement applications use this type of

unit.

The basic operating principle of differential pressure flow meters is based on the premise that the

pressure drop across the meter is proportional to the square of the flow rate. The flow rate isobtained by measuring the pressure differential and extracting the square root.

Differential pressure flow meters, like most flow meters, have a primary and secondary element.

The primary element causes a change in kinetic energy, which creates the differential pressure inthe pipe. The unit must be properly matched to the pipe size, flow conditions, and the liquid's

properties. And, the measurement accuracy of the element must be good over a reasonable range.The secondary element measures the differential pressure and provides the signal or read-out that

is converted to the actual flow value.


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ORIFICES

Orifices are the most popular liquid flow meters in use today. An orifice is simply a flat piece of

metal with a specific-sized hole bored in it. Most orifices are of the concentric type, buteccentric, conical (quadrant), and segmental designs are also available.

In practice, the orifice plate is installed in the pipe between two flanges. Acting as the primarydevice, the orifice constricts the flow of liquid to produce a differential pressure across the plate.

Pressure taps on either side of the plate are used to detect the difference. Major advantages oforifices are that they have no moving parts and their cost does not increase significantly with

pipe size.

Conical and quadrant orifices are relatively new. The units were developed primarily to measureliquids with low Reynolds numbers. Essentially constant flow coefficients can be maintained at

R values below 5000. Conical orifice plates have an upstream bevel, the depth and angle ofwhich must be calculated and machined for each application.

The segmental wedge is a variation of the segmental orifice. It is a restriction orifice primarilydesigned to measure the flow of liquids containing solids. The unit has the ability to measure

flows at low Reynolds numbers and still maintain the desired square-root relationship. Its designis simple, and there is only one critical dimension the wedge gap. Pressure drop through the unit

is only about half that of conventional orifices.

Integral wedge assemblies combine the wedge element and pressure taps into a one-piece pipecoupling bolted to a conventional pressure transmitter. No special piping or fittings are needed to

install the device in a pipeline.

Metering accuracy of all orifice flow meters depends on the installation conditions, the orificearea ratio, and the physical properties of the liquid being measured.

Venturi tubeshave the

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