Panki Thermal power Station

1. What is a POWER PLANT?

In this world at present time we think of any activity without electricity. Electricity

has become an integral part of our lives. From small house hold purposes to heavy industrial

works. Everywhere we need electricity. Where this electricity come from? It is the various

power projects, hydle power projects, nuclear power projects, etc. But the purpose remains

the same i.e. generation of electricity and that too at same specific frequency for a particular

country. A power plant converts one form of energy into another to finally obtain electrical

energy. In thermal, hydle and nuclear power project heat, hydraulic and nuclear energies,

respectively, are converted to electrical energy.

2. Major Thermal Power Projects In U.P.

In India there is a very long chain of thermal power projects in U.P. the various

thermal power projects are governed by different bodies N.T.P.C. and U.P.R.V.U.N.L.

(“Uttar Pradesh Rajya Vidyut Utpadan Nigam Ltd.” was earlier known as U.P.S.E.B.).

Some of the power projects under U.P.R.V.U.N.L. are:

S No. Name of the projects NO. OF UNITS Capacity

1. Harduaganj A 3 90

2. Harduaganj B 4 210

3. Harduaganj C 3 230

4. Panki 2 210

5. Obra 5 400

6. Obra Ext. 5 1000

7. Anpara 3 630

8. Anpara Ext. 2 1000

9. Pariksha 4 640

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3. About Panki Thermal Power Station

Panki thermal power station is one of the oldest stations of U.P.S.E.B. (Uttar

Pradesh State Electricity Board). This plant is situated in Panki industrial area of

Kanpur and is about 14 km away from Kanpur central station. The land acquired by this

plant is about 9 square km.

This power station started with small generation of 64 MW power consisting of 2

units of 32 MW each. Former Prime Minister Late Mrs. Indira Gandhi inaugurated it on

Saturday, September 09, 1969. Later in 1975, its generation capacity was extended to 284

MW with introduction of 2 more units each of 110 MW each. But in 1996, 64 MW plant

was closed on account of high pollution concern. At present the generating maximum

power of 210 MW.

Plant has total staff of 750 which includes:

1- General Manager (G.M.)

4- Deputy General Manager (D.G.M.)

12- Executive Engineers (Ex. En.)

50- Associate Engineering (A.E.)

70- Junior Engineers (J.E.)

Remaining skilled and unskilled worker.

Panki thermal power station (P.T.P.S.) has two main divisions, viz. B.M.D. (Boiler

Maintenance Division) and T.M.D. (Turbine Maintenance Division), former deals with

boiler function and later with Turbine.

3.1 The main raw materials used in plant are as follows:

Raw Material Source

Water Lower Ganga Canal

Coal Coal India Ltd., Bharat Coal Cooking Ltd.

Oil Indian Oil Corporation Ltd.

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Coal India Ltd. carries the coal supply to this plant. This coal is raw coal, which is

finally changed into pulverized coal. The ash produced in this process is disposed to near

by pond. This ash is given in free to ACC Cement Company for producing cement.

3.2 The Components at Different Levels

Height Components

0 m Turbine Section: Boiler feed pump condenser and oil pump.Boiler Section: Ball Mill.

8 m Turbine Section: Turbine.Boiler Section: Primary air fan, Electrostatic precipitator, Induced Draft fan, Forced draft fan.

13 m Boiler Section: Raw coal chain feeder, pressure reducing

18 m Boiler Section: Pulverized Coal Feeder.

26 m Boiler Section: Warm Conveyer, Pulverized Coal Bunker.

30 m Boiler Section: Vapors Fan, Classifier, Coal Hopper, Raw Coal Bunker.

36 m Boiler Section: Deaerator, Cyclone.

40 m Boiler Section: Boiler Drum.

42 m Boiler Section: Injector, Explosion Window.

3.3 General Working of Panki Thermal Power Station (P.T.P.S.)

The general working of Panki Thermal power plant can be understood through the

following steps:

1. Water is pumped from the canal to the treatment plant where it is completely

demineralized using various chemical agents and physical process.

2. Raw coal from mines is brought in the yard by means of railway wagons. The

coal is then pulverized using ball mills and then it is send to the furnace through

the conveyers.

3. The furnace is ignited initially using furnace oil and after reaching a certain

temperature the pulverized coal is injected in the furnace, simultaneously the oil

supply is cutoff.

4. Now, the water is completely demineralized, is fed to the boilers, where it is

heated and converted into steam.

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5. By means of draft fans, the pressure of superheated steam is increased in a pipe.

The steam of high pressure is send to the blades of turbines.

6. The rotation of turbine shaft as a prime mover to the generator resulting, which is

generated electrical power.

3.4 Various Divisions for Efficient Working of P.T.P.SP.T.P.S. has been divided in various sub divisions for efficient working and

maintenance. Each of divisions comprise of a group engineers operators, supervisors

and workers for furnishing efficiently a particular list of job pre-defined each

division. Here are various divisions along with the work.

1. Water Treatment Division: this division separates the physical and chemical

impurities of water.

2. Coal Handling Division (CHD): this division takes care of efficient supply

of oil and fuel to power plant.

3. Boiler Maintenance Division (BMD): this division looks after the efficient

working and performance of boiler. Its mounting, its accessories, feed pump as fan

and milling system etc.

4. Turbine Maintenance Division (TMD): this division looks after the

efficient working and performance of boiler, its mounting, its accessories, feed pump

as fan and milling system etc.

5. Electrical Maintenance Division (EMD): this division is responsible for

its electrical network and its element in the power station.

6. Control And Maintenance Division: this division take care of various

instruments fitted in the power plants for controlling the generation of electricity.

7. Electrical Distribution Division: this division looks after the distribution of

produced electricity to the grid.

8. Civil Maintenance Division: this looks after construction and maintenance

of various structures in power plant.

9. Operation General Division (O.G. 1 ): this division takes care of the

sanitation and cleaning etc of power plant.

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10. Operation General Division (O.G. 2): this division is responsible of the

management of power house. It deals with the salaries of the employees recording

and sending data related to the performance of the power plant to the head office and

pointing out errors add malfunctioning in the operation of various departments.

11. Store And Purchase Division: this division deals with the storage and

supply at various separate parts required in the power house along with the purchase.

12. Transportation Division: this division looks after the transportation of coal.

4. Water Treatment Plant

The water treatment plant is required as the water from the canal cannot be

directly used in the boiler because it contains physical and chemical impurities which

have adverse effect to a plant operation. The water used in the boiler is known as de-

mineralized water (D.M. water)

Water from the canal is drawn by the pump house where large physical impurities

such as stone, fishes etc are operated by a screen having a net. The water is converted

in D.M. water in following stages:

Floculator Plant: Here alum is added to water to precipitate dust particles in water.

Al is Alum neutralizes charge dust particles become heavy and settle down.

Bleaching powder limestone is also added to remove hardness along with chlorine

(liquid) which removes bacteria and organic materials. Chlorine dosing is must during

rainy day. The process of sedimentation is applied to remove heavier particles. Water

is now stored in C.S.T. (Condensate Storage Tank)

Sand Filter: these stages of sand filter are put across the flow so as to remove other

suspended particles if any.

Activated Carbon Filter: this filter is employed for removal of bacteria and organic

materials. It uses Anthracite (coal) for filter.

Degasser: here gases like carbon dioxide and oxygen and hydrogen are removed.

Cation Exchanger: At this stage the ions are absorbed by an ion exchange method

HCl and Resins (-ve) are principle ingredients of chemical filters present here. Water

becomes acidic due to addition of hydrogen ion.

Anion Exchanger: Negative ions are observed by carefully formulated resins (+ve).

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Mixed Exchanger: here remaining negative ions are extracted through resins. The

D.M. water is now ready which has following specifications:

Conductivity = 0.04 siemens/cm2.

PH = 8.5 to 9

Hardness = Nil.

PH desired in clear water is between 8.5 to 9.Phosphate dosing is done in end for this

purpose.

The total capacity of water treatment is to provide: 60 tons/hr.

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5. Coal Handling Plant

A simple schematic diagram of coal handling plant of P.T.P.S. is shown in the

figure titled (Layout pf coal handling plant).

The raw coal is brought to the power plant by means of wagons. At Wagon

Tippler transferring it into Wagon Tipper Hoppers (W.T.H.) empties the coal from the

wagon. W.T.H. the coal is passed to vibrators from where it is transferred to conveyors.

Conveyor carries coal to crusher house where big pieces of coal are separated in a

screen and sent to crusher through conveyors from where the crushed pieces are

transferred to another conveyor. These are smaller particles of size ranging between 20

mm to 40 mm or below. Then conveyor takes coal from where tipper transfers the coal to

R.C.B. (Rock Coal Bunker)

There are two suspension magnets present one over conveyors just before crusher

house and another over the conveyors just after the crusher house. These magnets remove

any metallic impurities moving on the conveyors along with the coal.

The whole process described above is valid when the coal brought by the trains

directly feeds the R.B.C. When there is no train available then coal comes from Coal

Yard. The coal from coal yard is dropped with the help of bulldozers in the hoppers from

where it is transferred to the conveyors and the process is repeated to carry coal to the

R.C.B.

When R.C.B. are full then the coal coming from wagon tipper hopper, after being

crushed is transferred conveyors can carry the coal to the stacker which spread the coal in

the coal yard with the help of boom conveyor. Boom conveyors can rotate 360 0 on the

stacker which itself can move on the track laid over the length of the coal yard.

Thus the coal get stored in the coal yard, which can be used when the goods train

carrying coal are unavailable. In P.T.P.S. more than one lakh tones of coal can be stored

in the coal yard.

Coal handling plant also takes care of the storage purification and supply of the

fuel oil which is used for mitta lighting up boiler furnace and generation of constant

temperature in furnace during normal operation.

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5.1 Technical details of coal handling

Raw coal bunkers:

Numbers: 1/unit

Type: rotor operated plate type

Size: operating -620 mm X 905 mm

Raw coal chain feeder:

Numbers: 3

Type: drag link chain

Length: 10.4 m

Width: 0.6 m

Capacity: 10-45 T/hr

Classifier:

Numbers: 3/unit

Diameter: 3300 mm

Method of control: vane control

Cyclone separator:

Numbers: 3/units

Size: 1600 mm

Efficiency: 82%

Vapor fan:

Numbers: 3/units

Capacity: 5400 cu m/hr

Speed: 1480 rpm

Temperature: 900 C (medium)

Warm conveyor:

Number: 1 unit

Length of conveyor: 17.2 m

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6. Milling System

In thermal power plant pulverized coal is used for produced heat in the furnace.

This is because the burning of this state of coal takes place completely and also there

is lesser problem in ash handling. The coal pieces size 20 mm to 40 mm are taken

from raw coal bunker (R.C.B.) and through raw coal chain feeder their coal piece to

break them too pulverized.

Ball Mills are providing with flue gases (about 3000 C) which help in drying the

coal and raise its temperature to about (85 to 90o C).this is a fan in the circuit called as

vapor fan which solve following purposes:-

1. It creates vacuum in the circuit so that the pulverized coal is sucked out of ball

mill with air.

2. If due to any reason the supply of coal to the ball mill is broken and flue gases

are continuously supplied then the temperature of the ball mill will rise

excessively high. To avoid this vapor fan, thus recirculation of pulverized coal

to the ball mill and so the temperature comes down.

3. Micro particles of the coal are directly sucked by the vapor with air and

supplied to the furnace chamber for combustion.

For cooling dry cold air is also supplied during recirculation. Cooling is must

because temperature become higher enough then coal catches fire.

Pulverized coal from the ball mill is passed through a classifier, which act as a

screen separating out the bigger particles from the pulverized coal and re-treating

them to the ball mill.

From the classifier the coal goes to the cyclone separator where coal particles are

separated form the air. The vapor fan pump air out and coal particles go to warm

conveyors via turniket. The warm conveyor delivers the coal to be stored in the

pulverized coal bunker (PCB). From PCB the coal goes to the furnace with the help

of primary air fan (P.A.F.). This fan takes air from primary air heater and pushes the

pulverized coal from all the four corners of the chamber.

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6.1 Technical Details of Milling

Ball mill:Numbers: 3/unit

Mill size 300/579

Rated output: 28T/hr for design coal of 50 HGI

Speed: 17.5 rpm

Quantity: 17 Cu m/sec

Temperature of the medium after classifier: 90o C

MOTOR-630kw, 990 rpm

Raw coal bunker closure:

Number of chain feeder: 4

Type: motor operated plated type

Size: opening 620mm x 905mm

Raw coal chain feeder:

Number per boiler: 3

Type: drag link chain

Capacity (each): 10-45 tons/hr

Classifier:

Number per boiler: 3

Type: Raymond

Diameter: 3300mm

Cyclone separator:

Number per boiler: 3

Type: SEA 1600/2

Size: 1600mm

Vapor fan:

Number per boiler: 3

Type: DI-1600-6b, radial

Capacity:

Design: 61200m3/ hr

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At M. C.R.: 54000m3/hr

Pulverized coal feeder :

Number per boiler: 16

Output: 6.5tons/hr (max.)

7. Boiler Maintenance Division

BMD has three sections:

1. furnace for 105MW unit

2. milling section for 105MW unit

3. ash handling section for 105MW unit

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7.1 About Boiler

Figure titled “SCHEMATIC DIAGRAM OF BOILER WITH ITS

ACCESSORIES” shows the 105MW boiler installed at P.T.P.S. along with its major

accessories. The boiler is a Balance Draft, Radiant, Dry bottom, Single drum, Natural

circulation, Vertical water tube construction with casing and the single re-heat. The

furnace is of pi-type with an upward path, horizontal path and the return path. It has a

refractory lined water wall and the maximum furnace temperature is 1233oC. the unit is

designed for a minimum continuous rating (MCR) of 375ton/hr and the pressure of

135kgf/cm2 and a system temperature of 540oC.

The furnace is arranged for dry ash discharge and is filled with burners located at

the four corners. Each corners burner is supplied with coal, oil and secondary

compartment.

7.2 Water/Steam Circuit in the Boiler

In the boiler tube water flows from boiler drum without the help of any motor.

This natural flow of water is known as natural circulation of water in the boiler. This

happens due to the fact that cold water is heavier than hot water, so cold water in the

boiler drum comes down from tubes, which are inside the furnace. In these tubes water

gets heated

And it gets converted into steam. The steam and hot water comes up through the

boiler drum. In this way the steam is generated in the boiler.

The down water wall header is a tube which surrounds the furnace chamber at

lower side circularly all the tubes of the boiler are attached to this lower water wall

header. Up-riser is also in tubular form and through it steam and feed water enter the

boiler. The pressure and the temperature in the boiler are 185kgf/cm2 and 535oC. The

boiler produced steam is only saturated steam to super heat this steam it is passed through

the super heater. But only dry saturated steam is passed through super heater while steam

in the boiler is yet wet. To separate wet particles we use three systems in the boiler;

Baffle plates, Cyclone and driver from the system the steam comes out as the dry steam.

Now this steam goes to the super heater. Super heaters consist of four stage of ceiling

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super heater, convection super heater and final super heater. From super heater the steam

goes to re-heater.

Re-heater is in two stages. First stage consist of tri-flux heat exchanger, which

absorbs heat from super heated steam as well as from flue gases the second stage is –Exit

super heater located in the horizontal pass as pendent tubular loops.

8. Boiler

The unit is designed for a maximum continuous rating 375 tons at a pressure of

139 Kg/cm2 and a steam temperature of 540oC. The feed water temperature is 440oC.The

steam generating unit is designed to meet the nominal requirements of 110 Mw turbo

generators Set.

1. The unit is a balanced draft radiant, dry bottom single drum natural circulation

vertical tube type, construction with skin casing and single heat system.

2. The furnace is arranged for dry ash discharge and fitted with burner located at

its four corners. Each corner burner comprises coal vapor oil and secondary air

compartments.

3. The unit is provided with three ball mills and accessories and arranged to

operate with intermediate coal bunker.

4. The steam super heater consists of 4 stages viz. ceiling, convection, platen and

final super heater. The ceiling super heater forms the roof of the furnace and

horizontal pass and as the rear wall of the second pass. While the platen are

located at the furnace exit, the portion above the furnace nose encloses the final

super heater.

Control of superheated steam temperature is achieved by two stages

spray at one located before the platen super heater and the other located before

the final super heater.

Re-heaters are in two stages, first being the triflux heat exchangers

located in the second passes which absorbs heat from superheated stem as well

as from flue gases. The second stage is exit reheaters located in the horizontal

pass as pendent tabular loops. Reheated steam temperature control is affected

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by the automatic functioning of three way control valves and under emergency

condition by an attempetarator located cold reheats lines.

5. Flue gas for drying the coal in the mills is tapped off after the triflux heat

exchangers. The quality is affected by the damper located in the hot flue gas

pipe leading to the mill.

Temperature control is affected by controlling the recirculation vapor at

the mill entry. Immediately, after the triflux heat exchangers, air heaters and

economizers are located.

6. The hot air for combustion from air heaters stage-2 led into the combustion

wind box located on the sides of the furnace. Four coal-air mix tare pipes from

pulverized coal bunker are connected to four coal bunkers nozzle for coal. The

turn down ratio of guns will be selected that it will be possible to use them also

for pulverized fuel flame stabilization while operating under loads below the

control point.

7. Taking in to consideration the high % of ash and relatively poor quality of coal

due regard has been paid to the wide to the wide pitching of tubes and to the

gas velocities across the heating surface areas.

8. In order to ensure reliable and continuous operation, ample spot blowing

equipments provided. There is short retractable steam soot blowers provided at

the top of the furnace. Fully retractable rotary type blowers are located for the

cleaning of secondary super heaters and final hearer re-heaters. The stem soot

blowers are electrically operated.

9. Two F.D. fans are provided per boiler. The F.D. fans is provided per boiler.

The F.D. fans are of axial type, driven by constant speed motor. The regulation

of quantity and pressure is done by inlet vane control.

The gases are sucked through the mechanical and electrostatic

precipitators by I.D. fans and delivered in to the chimney.

10. Two I.D. fans are provided each boiler. The I.D. fans are of axial type, driven

by constant speed motors. Inlet vane control effects the capacity change with

reference to load. Both I.D. and F.D. fans have been dimensioned taking the

minimum margins of 15%on volume and 32% on pressure.

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8.2 Technical specification for steam generating unit

Supporting structures

The supporting structure serves for arranging and suspending the water wall

system .steam super heater, re heater, economizer, air heater, galleries, insulation and

sheet. The entire sheet casing is so designed as to permit undisturbed expansion of

individual boiler parts and also avoid any damage to the boiler setting due to thermal

influence. The supporting structure is designed strong enough with reference to the

outdoor type of the boilers. A seismic coefficient of safety has been assumed for design

of supporting structure.

The structures steel works includes 8 main columns with necessary frames,

tracing etc. and the ceiling beams from which the unit is slung. It also includes the

auxiliary columns on either side of the boiler axis, serving for soot blower operation

galleries. The main columns are pitched at 10 meters, 6 meters, and 7.7 meters parallel to

the boiler axis and 7.5 meters perpendicular to the boiler axis .the auxiliary columns are

pitched at 5 meters from the main column perpendicular to the boiler axis.

Boiler drums and drum internals

Boiler drum is made of alloy steel plate of 87mm thick and has a diameter of 1800

mm. the drum is of fusion welded on hemispherical dishes ends. The drum dishes ends

are provided with manholes and manhole covers. The longitudinal and circumferential

wells are annealed and X-rayed during manufacture. The drum is provided with stubs for

welding on of all connecting tubes, such as supply tubes, riser tubes, super-heated steam,

and outlet tubes, feed water inlet tubes etc.

The function of drum internals is to separate water from the steam generated in

the furnace walls and reduce the dissolved solid content in steam below the prescribed

limit.

The drum internals consists of feed disturbing pipe, blow-down collector pipe,

turbo separators, screen dryers and other separating devices to minimize the carryover.

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Feed distribution pipes runs along the length of the drum, to which 10 tubes are

connected from economizer. Feed water is uniformly through the small holes in the

distribution pipe.

Steam water mixture entering the drum from the riser tubes and furnace walls is

collected in a separating chamber, formed by internal baffles. From this chamber, the

mixture is first led through two rows of turbo-separators. Each turbo-separator consists of

a primary stage and secondary stage.

The primary stage is formed by two concentric cans. Spinner blades impart a

centrifugal motion to the mixture of steam and water flowing upward through the inner

can, thereby throwing the water to the outside and forcing the steam to inside. The water

is arrested by a skim-off lip above the spinner blades and returned to the lower part of the

drum through the annulus between the two cans. The water proceeds onto the secondary

separator stage.

The secondary stage consists of two opposed banks of closely spaced corrugated

steels, which direct the steam through tortuous path force remaining entrained water

against the corrugated plates. Since the velocity is relatively low, the water dose not get

picked up again, but runs down the plates and off the second stage lips at the two streams

outlets.

From the secondary separators the stream flows uniformly and with relatively low

upward to the series of screen dryers, extending in layers across the length of the drum.

These screens perform the final stage of separation.

Rough mountings

These consists of access door into the combustion chamber, region of super

heaters, economizers and air heaters, as well as observation parts, explosion doors,

dampers in flue gas duct etc. the rough mountings are made of cast iron or are of

fabricated design depending upon the location and their purpose.

Water walls

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The combustion chamber is formed of water walls tubes of out side diameter 60.3

mm set at a pitch of 62 mm. in the corner where the pulverized coal burners are located,

the tubes are bent suitably to provide opening for the filling tangential burners.

The seamless water walls are welded to the bottom and top headers by means of

stubs. The top headers are connected to the boiler drum by means of tubes which are

welded-on to it by means of stubs.

The supply tubes supplying water to the down comer are welded to the drum by

means of stubs at one end and to the down comers at the other end. At the bottom supply

tubes connect the bottom water wall header and the down comers. Perfect naturals

circulation contours is ensured by adequate dimension of down comer and supply tubes

The guide and spring supporting suspension are so designed and depositional as to

proper expansion and contraction of the tabular system without occurrence of undo

stresses.

The water in the furnace walls absorbs heat. The resulting mixture of water and

stream is collected in the outlet headers and discharged into the stream drum through a

series of riser tubes. In the stream drum separation of water and stream takes place. In the

boiler, water mixes with the incoming feed water. The saturated is led to super heater by

a super heater connecting tubes.

Super-heaters

The stream super-heater has a total heating surface of 4919 m2. The super-heater

is composed of four stages viz. ceiling super-heater, convection super-eater, platen super-

heater and final super-heater.

The ceiling super-heater forms the roof of furnace and horizontal pass and

finishes as the rare wall of the second pass. The convection super-heater is made of

horizontal banks located in the second pass. The platens are located as the furnace exit

and the portion above the furnace nose enclosed the final super-heater.

The ceiling super heater forms the roof of furnace and horizontal pass and finishes

as the rare wall of the second pass. The convection super heater is made of horizontal

located in the second pass. The platens are located as the as the furnace exit ant and the

portion above the furnace nose enclosed the final super heater.

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Saturated stream from boiler drum is led through the transfer tubes to the ceiling

super heater. From there it is led to the convection super heater located in the second

pass. The first regulating injection is arranged at the end of the convection super heater

and before the inlet of the steam to the radiant platens the steam is led to the final super

heater. The second stage regulating injection is arranged between the platens and the final

super heater. The super heater tubes ate welded to the inlet and the outlet headers by

means of stubs.

Besides the arrangement of platen duper heater elements and grid tubes at the

furnace exit to ensure through mixing of the combustion products before they enter

convection super heater region, the super heater headers are given cross connections to

ensure good mixing effect on the steam site of the super heater also. The design and

deposition of the stages of super heater surface have been carried out so as to reduce the

effect of hydrodynamic non-uniformity on stem and gas sides to the minimum.

Super heated steam temperature control

Control of superheat temperature is affected by two stages of injection type

attemptators. First stage of de-superheating is in between the convection super heater and

platen super heater. The second stage is located between the platen and final super heater.

The supply is taken from feed pipeline before feed control station. Boiler feed water of

requisite quality is used for spraying purpose. Water spread into the stream to be

attemperated at a sufficient high pressure to ensure through attemperation.

Re-heaters

The steam re-heater having a total heating surface of 2564 m2 are made of

pendent and horizontal tabular loops and are in two stages. The first stage is one of

horizontal tabular arrangements and the principle of Tri-flux is used. The steam from

super heater flows through a tubs of outside diameter of 35mm, while the steam to be

reheated flows outside the tube through a bigger tube of outside diameter of 70mm. the

stem for the Tri-flux is drawn through a three way valve arranged in a connecting

between out let of platen super heater and inlet of final super heater. The second stage of

re-heater is suspended on the horizontal pass of the boiler as pendent tabular loops. The

re-heater tubes are welded to the inlet and exit heater by mean of stubs.

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Reheated steam temperature control

Tri-flux heat exchanger serves for the temperature control. Its design and function

is also described under item 2.7.the reheated steam flows through the heat exchanger in

full quantity corresponding to the rate of the turbine generator. The quantity of super

heated steam through the heat exchanger and thereby the thermal output depend upon

three way control valves.

The three way valves are arranged in the circuit of automatic control of the re-

heater steam temperature. An air temperature is also arranged in the cold reheat steam

pipe line to be used manually under emergency condition.

Economizers

The economizers with heating surface of 4930 m2 are made of seamless tabular

loops. The tubes of outside dia. 32mm are welded by means of stubs to the inlet and

outlet headers. The headers and horizontal loops rest on supporting structures of second

pass of the boiler with the provision for free expansion. The total economizer heating

surface e is divided into 8 assembly blocks are arranged in the second pass of the heat

recovery zone of the boiler so as to achieve recovery of heat in a very economic manner .

Fine fittings

These consist of the necessary number of safety valves on the boiler drum. Super

heater and re-heater pipelines, air release blow down and drain valves, boiler fees line,

fitting, direct remote water level indicators, boiler accessories such ss pressure gauges on

the drum, super heater and re-heater headers, economizers, thermometers for superheated

and reheated steam etc.

The fine fittings which will be delivered with in the scope of the boiler supply are

indicated in detail in the scheme of valves and fittings. The fittings and mountings

indicated have been chosen from established reputed sources of supply either India or

abroad. With reference to relevant requirements under the Indian boiler regulations 1950,

taking into account all the latest amendments.

Air pre-heater

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Air pre heaters provided are of tabular type air heaters. A total heating surface of

18720m2.they are made up of ERW tubes of dia 40mm, the ends of which are expended

into tube plates. The air heater is divided into two stages, the first stage having 8 heater

blocks and second stage having 4 blocks.

The air heater blocks are mounted on frames of the supporting structure, sealed

and bolted together, and they are from gas tight and air tight units. Provision has been for

the free expansion joints. The air heater is such that the flue gases in the vertical

direction, while the air to be heated flows out side the tubes in a direction perpendicular

to the flue gases.

Skin Casing Insulation and Outer Casing

The furnace walls arranged in tangential tube constructions are completely skin

cased with aluminum sheets. Skin casing to prevent air leakage is also adopted on the

finned tubes of the side walls of final re-heater region and the side walls, front and rarer

walls and the ceiling of the second pass. The ceiling above the secondary super heater

and final super heater will be having light refractory and insulation.

Cold and Hot Ducts

This include duct work from F.D. fan to air heater inter connected duct between

air heater blocks, the ducting to primary air fan, hot air duct to burners and at distribution

box.

Flue Duct

These include the duct between the air heater and economizer, the duct enclosing

the economizer blocks, the below the air heater and all ducting between the boiler and

chimney. Flue gas extraction duct leads flue gas extracted from second pass of the boiler

for drying of coal during pulverization. The lay out of flue gas extraction ducting

commences at the point of extraction of hot flue gases from the heat recovery zone of the

boiler and ends at the raw coal inlet to the ball mill. This flue gas extraction ducting is

made of alloy steel plates in view of the fact that the temperature of hot gases will be

around 500oC.

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8.3 Technical details of boiler

Boiler details

The steam generation unit has been designed to meet the requirement of a 110

MW (now degraded to 105 MW) turbo-generator set.

Manufacturer: Bharat Heavy Electric Limited

Type:

1. Radiant

2. Single drum

3. Pulverized coal feed

4. Indirect firing

5. Tangential firing

6. Water tube

7. Skin case

8. Natural circulation

9. Re-heater

10. Balanced draft

Maximum continuous rating: 375 tons/hr.

Maximum rating without stabilization: 240 tons/hr.

Rated steam pressure at super-heater outlet: 139 Kg/cm2

Rated steam temperature at super-heater outlet: 5400 C

Rated temperature of feed water at economizer inlet: 2400 C

Rated steam flow through re-heater: 324 tons/hr.

Rated steam temperature at re-heater inlet: 3600 C

Efficiency of the boiler: 86%

Design pressure of the boiler drum: 161 Kg/cm2

Design pressure of the boiler re-heater: 42 Kg/cc

Heating surfaces

Effective water wall area: 1223 m2

Super-heater: 4919

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m2

Tri-flux:

(a) flue gas side:920 m2

(b) steam side: 824 m2

8.4 Boiler mountings

(a) Water level indicator: indicates the level of water in the boiler.

(b) Stop valves: controls the supply as per requirement.

(c) Pressure gauge: shows the pressure of the steam in the boiler.

(d) Blow cock: blow cock is used to remove mud, scale or sediments collected at the

bottom of the boiler and to empty the boiler.

(e) Feed check valves: feed check valve is used to control the supply of water to

maintain constant level.

(f) Safety valves: it prevents the excessive steam in the boiler. It may be spring-

loaded type, dead weight type, lever type or high steam and low water type.

9. Coal firing system

The steam generation unit has been designed for firing coal and oil at low loads

for stabilization. The fuel firing equipment is designed such that the rated parameter

would be reached fuel is fired. The burners are located at corners of the furnace tangential

to imaginary circles, having their centers co-axial with the center of the combustion

chamber. At each corner, there are nine compartments arranged as mention below.

There are four coal burner nozzles, three vapor burners and two oil burners at each

corner. The four coal fuel system each of the nine compartments is provided with

independent air dampers. All the adjustable tips are stainless steel to withstand high

temperature.

9.1 Technical details of coal burners

Total burner: 16

Manufacturer: BHEL

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Capacity: 3.65 ton/hr

Type: tilting tangentially

9.2 Pulverized coal fired boiler

With the increased in the size of turbines, the boiler works also increase. They

now have to supply steam at a high temperature and pressure and the bulk quantity. In

such type of boiler coal is fed in pulverized form, which has following advantages:

1. Unlimited output capacity.

2. Even low grade coal can be burner.

3. Even very fine boiler output control is possible.

4. High efficiency.

5. Less possibility of unburned coal.

9.3 Fuel oil system

In the pulverized fuel fired boiler oil firing is used for safe and quick start-up of

boiler ignition of pulverized coal and to bring stability to coal frame under low conditions

of the boiler. Fuel oil designed for about 25% of boiler output with eight flexible oil guns,

two in each corner.

The oil guns are located at the top and bottom of secondary air nozzles and in

between coal nozzles. The oil guns are of pressure atomizing type.

10. Air cycle

Forced draft fan suck the air from the atmosphere. This passes through air heaters

(having three stages).

Air pre-heater are employed which extract heat from flue gases and give it to the air

being supplied to the furnace for coal combustion with the help of FD fan. This raises the

furnace temperature and increases the thermal efficiency of the plant.

This hot air is divided into two lines:

1. Primary air

2. Secondary air.

Primary air is sucked by PA wind box. This hot air is used for combustion of coal

properly.

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10.1 Specification of forced draft fan

Number: 2/unit

Capacity: 114480 cu m/hr, 56.2m3/s

Temperature: 340 C of medium

Speed: 1400 rpm

Type-NDFV22b

Pressure- 457 mmwc

Control- inlet guide vane

10.2 specification of induced draft fan

Type- NDZV 28slider

Capacity- 132 m3/s

Pressure-280 mmwc

Temp-150C

No per boiler-2

Speed-745 rpm

specification of primary fan

type-NDFV 20b

capacity-40 m3/s

pressure-1275 mmwc

temp-45 c

speed- 1480 rpm

11. Deaerator

This unit serves three purposes

1. It removes almost 98% air coming from any pump.

2. It removes the oxygen present in remaining air (here we done hydraulic dosing).

Here 99.8% of oxygen gets removed.

3. It removes air coming from leakage and maintains the vacuum in the condenser;

the air is removed with the help of ejector.

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We remove oxygen otherwise it will do oxidation or say rusting of boiler tube and

shell it will get weaker (as more and more heat will be required to generate the steam).

12. Turbine Maintenance Division

The steam has been used predominantly as a prime mover in all thermal power

stations. They convey the stored mechanical energy in steam into rotational mechanical

energy. The thermal energy of steam delivers to the turbine is converted into the kinetic

energy of the steam flow. The jets of high velocity steam are then directed to a ring of

blades that are free to revolve. These rings are fixed to the rim of revolving rotor. In a

modern steam turbine, there are several wheels of moving blades which keyed to the

same shaft. Between each row of moving blades, there is a ring of fixed blades, there

stationary blades are fixed to the turbine casing & they face in opposite direction to

moving blades. The function of fixed blade is to receive the steam jet coming out of

moving blade ring & to divert it to the next moving blade rings by changing its direction.

12.1 Type of turbines:

Impulse Turbines: The steam coming out at a very high velocity through a fixed nozzle

impinges on the blades fixed on the periphery of rotor the blades fixed on the periphery

of rotor. The blade changes the direction of steam flow without changing its pressure.

The resulting motive force gives the rotation to the turbine shaft.

Reaction Turbine: The high pressure steam comes out through these nozzles, velocity of

steam increases relative to the rotating disc. The resulting reaction force on nozzle gives

the rotating disc. The resulting reaction force on nozzle gives the rotating motion to the

disc and shaft. They rotate in the opposite direction of steam jet.

At panki thermal power station, impulse reaction turbine is used. Here the steam

expands both in fixed & moving blades continuously as the steam passes over it therefore

a gradual & continuous drop in pressure takes place.

12.2 Compounding of Turbines; In the thermal power stations where the

generators run at 3000 r.p.m., single stage turbine (one ring of stationary nozzle & one

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ring of rotating blades) is undesirable. To get the reasonable blade tip speeds in turbines,

the method known as ‘compounding’ is employed. In this method number of rotor in

series, keyed on same shaft, is used & the steam pressure& jet velocities absorbed in

steps as it flows over the moving blades.

Velocity compounding

There is only one set of nozzles and two or more rows of moving blades. There is also a

row of fixed blades in between the moving blade. The function of fixed blade is to

receive the steam jet coming out of the pressure and velocity of the steam. The heat

energy drops takes place only in nozzle at the first stage and is converted into kinetic

energy. Kinetic energy of the steam gained in the nozzles is successfully used by the rows

of moving blades and finally exhausted from the last row of the blades on the turbine

rotor. A turbine working on this principle is known as velocity compounded impulse

turbine e.g. Curtis turbine.

Pressure compounding

A number of simple impulse turbine sets arranged in series is known as Pressure

Compounding. Here the turbine is provided with one row of fixed blades (works as the

nozzle) at the entry of each row of moving blades. The total pressure drop of the steam

does not take place in the single stage nozzle but it is divided equally in all the rows of

the fixed blades, which works as nozzles e.g. Retreat turbine.

Pressure and velocity compounding

This is the combination of pressure and velocity compounding. The total pressure

drop of the steam from boiler to condenser pressure is divided into number of stages as

done in pressure compounding and velocity obtaining in each stage is also compounded.

This arrangement requires less stages and compact turbine can be designed for a given

pressure.

12.3 Technical details of turbine

Power

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Rated: 100 KW

Actually required: 740 KW

Rated voltage: 6600 V

Number of phases: 3

Voltage and frequency:

Full load r.p.m.: 990 r.p.m.

Full load current: 104 Amp.

Full load frequency: 94%

Torque: 4.63 Nm

Frequency: 50cycles/sec.

Terminal connections

Type: star

Number: 6

The 6 leads are taken out in the terminal box and connected on 4 bushes to form a star.

12.4 Generator and exciter

The electric generator is the most important part of the power station. The

principle of electromagnetic induction is used in the generation of electric power with the

help of electric generator. All modern type of AC generator essentially consists of fixed

starter and revolution rotor. The starter core carries a winding in which alternating emf is

induced when the shaft of the rotor is revolved with help of prime mover.

The rotor provides magnetic flux to the machine. The winding of 3 generators

may be connected either in delta or star arrangement. With star arrangement two voltages

can be obtained as line voltage and phase voltage. The neutral is connected to the earth

and this help in designing the protective s/m. in order to keep the temperature rise of

various parts have the generator and winding insulation from exceeding the maximum

permissible values. Every generator requires continuous cooling during its operation. The

s/m adopted for coiling at part that is closed. In the s/m cooling fans circulates the air

through the alternator and warm air is cooled by water coolers before being circulated

again. This s/m gives good protection against fire in alternator due to restricted air

supply. Carbon dioxide can also be easily injected to extinguish the fire.

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The exciter provides the DC current mended to excite the rotor field magnets. The

present excitation must be absolutely reliable since their failure will shut down the

alternators. The higher the load and more the lagging power factor, the greater excitation

is required.

13. Steam cycle

Water is converted to steam in the boiler and this steam is superheated in the

super-heaters. These heaters are ceiling super heater, primary super heater, platen

radiation, sober heater and finally exit super heater. This steam then enters the high

pressure turbine through the nozzle. The high pressure is both velocity and pressure

compounded impulse turbine. Here the steam rotates the turbine shaft by doing work on

the blade having pressure 135 kg/cm2 and temperature 5350 C. From high pressure

turbine parts of steam is extended and provided to high pressure heater 2. After high

pressure turbine the steam is reheated in re-heaters and then it goes to second casing of

then turbine called medium pressure turbine. Here the pressure of steam becomes 35

kg/cm2 and temperature 5150 C. from here small part of steam is extracted from four

different stages to supply the different heaters of feed water from medium pressure

turbine the steam goes, without being reheated, to low pressure turbine where it expands

completely to the condenser pressure 0.8 kg/cm2 and temperature 1000 C. A part of steam

is again extracted from medium pressure turbine and provides to low pressure heater 1, 2

and 3.finally the steam goes to condenser to where it get condensed and stored in hot

well.

14. Condensate water cycle

In condenser the steam is condensed with the help of cold water pump. The

condenser is a multi-tubular surface condenser in which cold water flows inside number

of tubes around which the steam to be condensed is present. The water from the hot well

is extracted and re-circulated with the help of condensate extraction pump (C.E.P.).

C.E.P. is a six stage vertical position pump. Taking the water from condensate storage

tank (C.S.T.) with the help of condensate pump fulfill the quantity lost during the cycle.

Thus condensate water passed through re-generative stages of turbine so that lesser fuel is

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required for generation of steam. These heaters are Gland Steam Condenser (G.S.C.)

chimney steam condenser (C.S.C.), low pressure heaters 1,2,3,4, and 5. Water from LP

heater goes to H.P. heater via dearater. Below the deaerater a boiler drum is also present,

where condensate water is stored. Thus, from condenser to deaerator, water cycle is

known as condensate water cycle in which several stages of heaters are also present.

15. Feed Water Cycle

After deaerator the water is pump to the boiler with the help of boiler feed pump

(B.F.P.). This pump creates necessary pressure head to feed the water to the boiler. It is

six stages in horizontal position. On it way to boiler the water passes through HP heaters

and economizers.

H.P. heater reheats the feed water to improve the boiler efficiency. The source of

heating is the steam exhausted from hp turbine and IP turbine.

Economizer extracted waste heat from out going gases to the feed water and then

it passes the feed water to boiler.

In this way we extract the maximum heat and improve boiler efficiency.

16. Ash Handling Plant

In the boiler furnace the combustion of coal is performed by hot air and produced

heat is used to generate the steam. After combustion of the coal and air changed in ash

and hot flue gases.

The air exhausted from firing zone contains 40% of O2, SO2, CO2, and NO2 as

impurities. This air is known as flue gases.

The flue gases are now directed to the electrostatic precipitator. On this way to

electrostatic precipitator this gas is used in economizer and several other heaters to

increase the boiler efficiency. On this way to the chimney is placed electrostatic

precipitator in which the ash is removed and then mixed with water to form slurry and

mixed with ash slurry from furnace itself.

Ash handling plant

1-Bottom Ash system 2- Fly Ash system

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Bottom Ash system

About 10% of total ash produced in the boiler falls into a mild steel fabricated refractory lined, water- impounded, storage type existing bottom ash hopper where it is stored and periodically discharged to the clinker grinder and hydro- ejector for transfer through the transport line once in 8 hour shift. The bottom ash hopper is designed for 8 hour capacity of ash.

Fly Ash system

Fly ash collected in ESP, falls through manually operated ms adopter, plate valve, expansion joints, ms adopter with y piece, cone valve to mixing box called flushing apparatus. The flushing apparatusServes to mix the ash with low pressure water and discharged the ash in the form of slurry into sloping sluicing channels provided beneath them. the removal of fly ash is continuous. However, removal capacity of mixing box bellow first two fields of ESP is 10 Tonnes / hr and rest is 2 Tonnes/hr

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ASH WATER SYSTEM

Water required for ash handling system is given by ash water pump which takes suction from discharge of circulating water system that is after condenser.which supply water for the following purpose.1-Hydroejector2-ejector feed sump3-Flushing header in bottom ash hopper4-Ash slurry sump make up5- ash slurry sump flushing nozzles6-all flushing apparatus bellow ESP7- Flushing nozzles of ash trench

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ASH DISPOSAL SYSTEM

The ash slurry, bottom ash,collected in the ash slurry sump pit is pumped to disposal area about 2 km away from the ash slurry pump house by hydro-seal ash slurry pump through 300 nb and 250 nb pipe lines. Out of 4 pumps ,2 run continuous ,1 intermittent ,1 stand by. Agitator nozzles in ash slurry sump keep the solids in floating stage.

DRY ASH EXTRACTION & TRANSPORTATION PLANT

16.1 Ash Handling / Draft Circuit

In the boiler furnace the combustion of coal is performed by hot air and produced

heat is used to generate the steam. After combustion of the coal and air, they are changed

into ash and hot flue gases.

The exhausted from firing zone contains 40% of O2, SO2, CO2, and NOx as

impurities. This is known as flue gases.

This flue gases along with coal are directed towards electrostatic precipitator

(ESP). On its way to ESP the gas is used by economizer and various other heaters to

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increase the boilers efficiency. On this way to chimney is placed ESP in which the ash is

removed and is mixed with water to form ash slurry.

There are two fans in the circuit of combustion gases from furnace chamber to the

chimney. There is induced draft fans and forced draft fans to suck gases from the circuit

and so it is situated near to the chimney. In this way it tries to create a vacuum in the

furnace. To neutralize this effect forced draft fans situated at the boiler side blows gases

in the circuit in this way due to slight pressure difference created by these fans

combustion gases and the products flows from the furnace chamber towards the chimney.

Working of induced draft fan and forced draft fans are so that the flame in the

furnace remains centralized. If the color of flame is not proper that is if flame is not

proper and not centralized then localized heating occurs and the water tubes may break

down.

16.2 Specification of Induced Draft Fans

Number: 2/unit

Capacity: 367200 cu. m/hr

Temperature of ambient air: 1450 C

Speed: 990 rpm

16.3 Electrostatic Precipitator (E.S.P.)

It essentially consists of two sets of electrodes which are insulated from each other. One set is called as emitting electrode and other is called as collecting electrode and other is called collecting electrode. The emitting electrodes are placed at the centre of pipe (tubular type precipitator) or mid way between two plates (plate type). The emitting electrodes are connected to the negative polarity of high voltage dc source of 40 KV. The collecting electrodes are connected to the positive polarity of the source and are earthed. A high electrostatic field is maintained between two sets of electrodes. This creates corona discharge and ionizes the gas molecules as the flue gas flows through the tubes or in between the plates. The dust (ash) particles in the gas acquire negative charge and are attracted to the opposite charge, where they get deposited. The deposited dust is made fall off the electrodes when they are rapped mechanically.

Electrostatic PrecipitatorThe Electrostatic Precipitators are extensively used in the most of power plant to remove the fly ash from flue gas. The use of this collector is growing rapidly because this is more effective to remove very fine particle range .01 microns to 1.0 micron. Which are not

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separated other separator like mechanical separator and wet scrubber etc. it is also most effective for high dust loaded gas ( as high as 100 gm /m3 ).its efficiency is as high as 99.8% .draught loss of this separator is least among all separator. Maintenance charges are moderate. It provides ease of operation .dust is collected in dry form and can be collected either dry or wet. Apart from these advantages some disadvantages also. As here DC current is used therefore considerable electrical equipment is necessary to convert 0.4 kV ac to 70 kV dc. This increases the capital cost. The running charges are also considerable high as amount of power re4quired for charging is considerable large. However in spite of cost it is used with pulverized coal fired station for its effectiveness on a fine ash particle compared with other type of collector.

Working principle

The Electrostatic Precipitator essentially consists of two sets of electrodes called Collecting Electrodes and Emitting Electrodes .The collecting electrodes is made up of steel sheet pressed to a special profile and emitting electrodes is a thin wire drawn to a helical form. A DC high voltage is applied between these electrodes, connecting its negative polarity to the emitting electrodes and positive polarity to collecting electrodes which are also earthed. The dust laden flue gas from boiler passes between rows of collecting and emitting electrodes. The high voltage induces ionization of gas molecules adjacent to the negative charged emitting electrodes. The positive charges of ions created travel towards the emitting electrodes and the negative charges towards collecting electrodes, on their way to the collecting electrodes, the negative charges get deposited on the dust particles. Thus the dust particles are electrically charged. In the presence of high electric fields between the electrodes the charged dust particles experience a force which causes the particles to move towards the collecting electrodes and finally get deposited on them. A minor portion of dust particles which have acquired positive charges get deposited on emitting electrodes also. Periodically these are dislodged from the electrodes by a process called Rapping. The particles then fall into the hoppers at the bottom.

Parts of ESP

The various parts of the ESP are divided into two groups.1. Mechanical system- it comprises casing, supporting structure and support

bearing, hopper, gas distribution system, collecting and emitting system, rapping mechanisms, stairways and galleries.

2. Electrical system- it comprises transformer –rectifier units, Electronic controller, auxiliary control panel, safety interlocks and field equipments/ devices.

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MECHANICAL SYSTEM1.Supporting structure and support bearing-The supporting structure of ESP is rigid frame structure capable of supporting the tire load of entire ESP collecting dust and additional vertical loads due to wind and earth quake. Diagonal members are provided to transfer the horizontal forces on the ground without generating any movement in the members. So all the members are designed for axial forces only. Site welding of the joints are critical and should be carried out with great care. Support bearings are provided between casing columns and supporting structure to ensure that the casing moves freely over supporting structure due to thermal expansion. These structure bearings are provided with PTFE lining to take horizontal movement and spherical surface to angular movement. Side guides are provided to take horizontal forces coming on the support point. The guide of bearing should be kept parallel to the line joining fixed foot of ESP and the particular support point. Mirror finished surfaces should be protected from any damage.

ESP CASINGESP CASING

2. Casing-The precipitator casing is an all welded construction .consisting of pre- fabricated wall and roof panels. The casing is provided with inspection doors for entry into chamber. The doors are of heavy construction with machined surface to ensure a gas tight seal. The roof carries internals, insulator housings, transformer etc. The casing rest on supports which allow for free thermal expansion of the casing during operation. Galleries and stairways are provided on the sides of casing for easy access to rapping motors, inspection doors.

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3. Hoppers-

ESP HOPPERSESP HOPPERS

Pyramidal hopper is provided under the casing of ESP to collect the dust. The hoppers are designed with a valley angle of not less than 55 deg to facilitate free fall of dust in hopper. Baffle plates are provided in each hopper to avoid gas sneak age. An inspection door is provided on each hopper. Thermostatically controlled heating elements are arranged at the bottom portion of the hopper to ensure free flow of ash.

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4. Rapping mechanism for collecting electrodes-

The system employs tumbling hammers which are mounted on a horizontal shaft in a staggered manner, with one hammer( 4.9 kg) for each shock bar. There are 47 hammers in fields in one collecting rapping shaft which is driven by horizontal geared motor with out put speed 1.1 rpm. As the shaft rotates slowly, each of hammers in turn balances and tumbles hitting its associated shock bar. The shock bar transmitted blow simultaneously to all of the collecting plates in one row because of their direct contact with shock bar. The shaft is connected to geared motor mounted on the side of the casing. The frequency of rapping is adjusted by controlling the operation of the geared motor by means of programmer, mounted in the auxiliary control panel.

16.4 Ash Handling Circuit

There are two fans in the circuit of combustion gases from furnace chamber to chimney. There are I.D. (induced draught) fans and F.D. (forced draught) fans. I.D. fans suck gases from the circuit and also it is situated near the chimney. In this way it tries to create the vacuum in the circuit. To neutralize this effect F.D. fans are situated at boilers side so that a slight pressure difference is created and the flow of gases takes place from the furnace chamber to the chimney. Working of I.D. fans are so set that the flame in the

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furnace remains centralized, if the flame is not centralized then localized heating occurs and water tube may break down.

17. Cooling water cycle

Panki thermal power station has two separate systems for cooling water cycle, which depends upon the availability of water in canal. They are:

(a) Open loop cycle (b) Closed loop cycle or auxiliary water cooling cycle.

17.1 Open Cycle

When the water is sufficient in the canal, then this cycle is used. Here the water is drawn from the pumps. This water cools the turbine exhaust. The drop in temperature is about 10-150 C after cooling. Then water goes back to canal.

17.2 Closed Loop or Auxiliary Water Cooling Cycle

When water is scarce (usually during summer), this is used. The only difference in this cycle from open loop cycle is that cooling water coming out of condenser goes to cooling tower where it is dropped from the certain height. Thus reducing its temperature by 4-50C per fall. After cooling this water is again sent to pump house which recycle it.

19. Control and Instrumentation

This is the back bone of a thermal power plant. Various parameters in various

auxiliaries are controlled from here. All the equipment in this room is imported. The

equipment is very sensitive and can pick up even minute disturbances. Automatic

controlled compared the actual value of plant out put with the desired values determines

the deviation and produces control signals with the desired value determines the deviation

to zero or a small value. Industrial automatic controllers that are employed in the control

and instrumentation sections are as follows:

Two position or on-off controllers.

Proportional controllers.

Integral.

Proportionally-Integral controllers (I.P.)

Dsesiraty controllers.

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Proportionality Integral Derivative controllers(P.I.D.)

Boiler drum indicator

There is lot of red and green in the control room. The light continuously indicates the

boiler drum steam and water level. When the level goes in the danger region on alarm is

actuated.

Feeding desk

On this panel the knobs are available for the operations. Steam dust collectors are

measured in these stages. The boiler pressure is indicating by corresponding dial. When

the boiler steam reaches the superheated and attains a temperature of 4500 C. this steam

released to the turbines. A temperature higher then the allowed value is indicated by an

alarm. A control panel also indicates pressure in the boiler tube. There is also present coal

burner control. For the initial firing we require coal temperature of 800-10000 C. The

primary air fan controls the pressure of air.

Pulverized coal feeding desk: when vapor is fully open the pulverized coal feeder

will start otherwise and pipe line will be headed.

Furnaces draft control desk: by this vacuum and quantity is maintained quick

closing valve are provided.

Vibration

Vibratory pick ups are to pick uo the vibration and then amplified scientific pick

ups are used to pick up displacement of even or few micrometers.

M.P. expansion

Differential expansion of stator frame is observed at turbo supervisory equipment

because if it becomes more than they may break. Maximum and minimum allowable

expansion in different section is shown below:

Turbine pressure Minimum Maximum

High pressure 1.5 mm 3.5 mmMedium pressure 1.5 mm 3.5 mm

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Low pressure 2.0 mm 4.0 mm

Bearing temperature

Bearing are made of those metals, which melt at 1000 C. therefore allowable

temperature is 7.50 C. platinum resistance thermometers are used.

Oil pressure

The oil pressure is maintained at 35 kgf/cm2 at the header and pressure of 15.8

kgf/cm2 at ball bearings.

n

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CONCLUSION

PANKI THERMAL POWER STATION with 2 generating units of 32 MW

capacity each along with associated and related equipment such as generators, turbines,

boilers, cooling tower, secondary fuel oil storage facilities and its handing system,

switchyard including step-up transformers, step-down transformer, raw materials etc. and

works in progress.

PANKI THERMAL EXTN. POWER STATION with 2 generation units of 110

mw (dearated to 2*105 MH) capacity each along with associated and related equipment

such as generators, turbines, boilers, cooling tower, secondary fuel oil storage facilities

and its handing system, switchyard including step-up transformers, step-down

transformer, raw materials etc. and works in progress.

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