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A

PROJECT REPORT ON

“Boiler and its auxiliaries”

In accordance with 2-week Training

At C.S.T.P.S.

Submitted By:-

Uday Wankar Sainath Sorte

Anant D. Patil Shubham Asati

Sankalp Guremukhi Pratik Raut

Rohit Lonjekar Mangesh Jumnake

Surendra Butale Vivek Talande

Azhar Sheikh Atul Bhusari

Anup Mathankar Vivek Dhote

Rahul Chekbandalwar Ashish Dhande

Nikhil Shriramwar Gunjan Jaspal

Shivprasad Bhosale Bhushan Lode

Under the Guidance of

Er. A. G. Raut

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INDEX

1. INTRODUCTION ……………………………………..………………………………..2

1.1 About C.S.T.P.S. …………..……………..……………………………...……2

2. THERMAL POWER STATION ……..………………..……………………………….. 3

2.1 An Overview ………………………..……..………………………………….…..3

3. PRICIPLE …………………………………………………..……………………….….. 4

3.1 Rankine Cycle ……………………………………………………………….……4

4. Design ………………………………………….………………………………………..6

4.1 Construction and Components …….……………………………………….……6

5. WORKING ………………………………………………….………………………..…8

6. BOILER AUXILERIES …………………………………….…………………………12

a) Fans …………………………………………………………………………….….12

1) I.D. Fans ………………………………………………………….12

2) F.D. Fans ……………………………………………………...….13

3) P.A. Fans ………………………………………………………….13

4) Seal air Fans …………………………..……………………….….14

5) Scanner Fan Fans …………………………..………………….….14

6) Ignitor Fans ……………………………………………………….14

b) Coal Feeder ……………………………………………………………………….15

c) Coal Mill ………………………………………………………………………….15

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d) Air Pre-Heater …………………………………………………………………….15

e) Clinker Grinder ……………………………………………………………….….16

7. BOILER LIGHT-UP PROCEDURE …………………………………..………….…..17

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INTRODUCTION: About CSTPS

MSEB was set up in 1960 to generate, transmit and distribute power to all consumers in

Maharashtra excluding Mumbai. MSEB was the largest SEB in the country. The generation

capacity of MSEB has grown from 760 MW in 1960-61 to 9771 MW in 2001-02. The customer

base has grown from 1,07,833 in 1960-61 to 1,40,09,089 in 2001-02.

C.S.T.P.S in contribution much in field of production of electricity. It is not only number

one thermal power station in Asia but also has occupied specific position on the international

map.

The first set was commission on August 1983 & was dedicated to nation by then PM

(late) Mrs. Indira Gandhi & second set commission on July 1984. The third & fourth units of

CSTPS under stage 2 were commissioned on the 3rd May 1985 & 8th March 1986 respectively.

The units 5 & 6 were commissioned on the 22nd March 1991 & 11th March 1992 respectively one

more units of 500MW was added to the CSTPS on making its generation to 2340 MW &

making “C.S.T.P.S.” as the giant in Power Generation of CSTPS.

STAGE 1:- 2 * 210MW units

STAGE2:- 2 * 210MW units

STAGE3:- 3 * 500MW units

Location of plant:-

Plant is situated about 7km away from Chandrapur Railway Station by the

side of Tadoba National Park road.

2. Climate condition:-

Daily average ambient temp 40c

Maximum ambient temp. 50c

Minimum ambient temp. 5c

Altitude for min sea level 192.3m

3. Total land area required:-

Main plant including CHP & Railway sliding: 11256 hec

Ash disposal area: 1117 Hec.

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THERMAL POWER STATION: An Overview The basic operation of any thermal power plant is based on the Rankin modified cycle.

Operation can be described as follows:

Coal is taken to coal storage from nearby mines. In CHP, the coal is converted into fine

powder called ‘pulverized coal’, because it gives complete combustion & hence better efficiency.

This fuel is fed to furnace of boiler for the sake of combustion. Boiler converts water into steam,

which is called saturated steam because it has some moisture content. This steam is further

heated in super heater at about 540 0 c so as to remove the last traces of moisture from the

steam before feeding it to the turbine. This superheated steam is passed over blades of turbine,

work done in the form of rotation of turbine & pressure drop is observed. It means high pressure

steam is converted into mechanical energy.

The turbine is mechanically coupled with rotor of three phase alternator & thereby acts as

prime mover to it. Hence as per faraday’s law of electromagnetic induction, the alternator

produces 3-phase electric power as its output terminal. The steam after doing its useful working

the steam is then condenses in condenser i.e. again converted into water, i.e. recirculated in the

cycle using boiler feed pump & economizer.

Fig.2 Energy conversion taking place in the thermal power plant

Chemical Energy is converted to Heat Energy by combustion of fuel in boiler

Heat energy converts water to high pressure, high temperature steam.

In Turbine, steam expands as it is passed through number of nozzles. Heat energy is thus converted to kinetic energy.

Steam is admitted to Turbine through pipes.

Steam is then passed over blades, arranged on shaft of Turbine. Shaft rotates & Kinetic energy is thus converted to mechanical work

Steam exhausted from turbine condenses in Condenser, rejecting unavailable heat energy.

Pump delivers condensed water from Condenser back to Boiler.

Generator is coupled to Turbine, where mechanical energy is converted to electrical energy.

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PRINCIPLE: Rankine cycle

Fig: Temperature verses Entropy Characteristics

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 a liquid at this stage the pump requires little input energy.

Process 2-3: The high pressure liquid enters a boiler where it is heated at constant

pressure by an external heat source to become a dry saturated vapor. The input energy required

can be easily calculated using mollier diagram or h-s chart or enthalpy-entropy chart also known

assteam tables.

Process 3-4: The dry saturated vapor expands through a turbine, generating

power. This decreases the temperature and pressure of the vapor, and some condensation may

occur. The output in this process can be easily calculated using the Enthalpy-entropy chart or the

steam tables.

Process 4-1: The wet vapor then enters a condenser where it is condensed at a

constant pressure to become a saturated liquid.

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In an ideal Rankine cycle the pump and turbine would be isentropic, i.e., the pump and

turbine would generate no entropy and hence maximize the net work output. Processes 1-2 and

3-4 would be represented by vertical lines on the T-S diagram and more closely resemble that of

the Carnot cycle. The Rankine cycle shown here prevents the vapor ending up in the superheat

region after the expansion in the turbine, [1] which reduces the energy removed by the

condensers.

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DESIGN: Construction and Components

Boiler means any cleared vessel exceeding 22.75 LH in capacity used for steam.

Generation under pressure.The first Boiler developed in 1725 & working pressure was 6 to 10

kg/cal.

TYPES OF BOILERS: There are two types of Boilers:-

1) Fire tube boilers (Carnish & Lauchashine blrs.) developed in the year 1844

2) Water tube boilers developed in 1873 years.

We are having in Thermal Power stations water tube Boilers.

These are sub divided according to water circulation, as :-

1) Natural circulation: Drum to down comers to due ring main header to water wall

tubes & back to drum difference in density of water when cool & hot.

2) Forced circulation: Additional pumps are installed in down comers.

According to pressure the Boilers are called-

1) Drum type sub critical boiler: When boiler pressure is 130 kg/cm2 to 180 kg/cm2

2) Critical pressure Boilers : When boiler pressure is 221.2 kg/cm2

3) Super critical drum less once through boilers: When boiler pressure is 240 kg/cm2

All modern Boilers are top slung from steel structures from the Beams a series of slings

take up the boiler loads. Suspended weight of one 210 MW boiler is 3640 tonnes approx. eight of

Boiler is about 64 meters and Boiler drum is at a height of 52 meters from ground.

Boiler design:

1. Lowest capital cost, ease of construction, simplicity, s\safety, Good working condition

ease of maintenance

2. Efficient operation, effective baffling for heat transfer will insulate casings, ability to

deliver pure steam with effective drum internals, build steam ball capacity.

3. Availability of auxiliaries

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The main parts of Boiler are:

Boiler drum (Length: 15.7 meters, ID: 1976 mm, Thickness 132 mm) down comers (6

down comers of size 406x32 mm)

Water walls (Made of SA 210 Gr A1 material, 63.5x6.3 mm, 76.1mm thick)

Furnace (13.868 m width, 10.592 m depth, 5494m3 vol)

Platen superheater (The size of tubes are 51x7.1 mm +51x8.6mm)

Reheater (The size of tubes is 54x3.6 mm)

Final superheater (size of tubes are 51x7.6 mm the materials are SA213 T22 alloy steel

and stands upto 5800C (alloy steel)

Primary superheater (The material used are SA209T, SA210 Gr. A, SA 213 T11.The

size of tubes are 44.5x4.5 mm & temperature range is 4500C to 4800C

Economizer (The material used are carbon steel of SA 210 Gr. A1 stands upto 4500C,

size of the tubes are 44.5x4.5 mm)

Burners (The burners are situated at 3 elevations called AB,CD,EF)

Ignitors (For every burner one ignitor is provided for igniting the burner for

combustion & cooling ignitor fan is provided. It is a centrifugal fan with backward

curved. Capacity 9000 m3/h, 75 mm WC, 1500 rpm.

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WORKING:

In Boiler, Coal is stored in Bunkers. Size of coal in bunkers is 25 mm. The coal received

from coal mines has a size varying from 4 to 8 inches. In Coal Handling plant, it is first reduced

to 25-mm size and then fed to the bunkers through a series of conveyer belts. From bunkers, coal

is fed to the Coal Mill where it is pulverized. Coal particle average size, after pulverization, is 75

microns.(1 micron is 1000th part of a millimeter) In 210 MW units, there are 6 coal mills and in

500 MW units, 8 coal mills are installed. For full load operation of the unit, 4 to 5 coal mills are

running. Other coal mills are stand by.

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When boiler is to be started up from cold conditions, coal can not be fired, as there is no

ignition energy available. Hence first L.D.O. is fired for lighting up the boiler. After Boiler

pressure is built up to certain specified values, Heavy Furnace oil is fired. After achieving the

specified parameters with oil firing, coal is admitted.

Pulverized coal from the mills is continuously lifted with the help of air, called primary

air. Primary air fans are installed for this purpose. Coal-air mixture is fed to Boilers through coal

burners, arranged at various elevations. For complete and efficient combustion of coal, primary

air is not sufficient, and hence secondary air, obtained from Secondary Air fans, is also admitted

to the furnace in controlled quantity. Before admission in coal mills and boiler, primary air and

secondary air are first heated to a temperature of 325° C.

Heating of air is carried out in Air pre heaters, with the help of hot flue gas leaving the

boiler. When coal is burnt, it also produces ash. Small ash particles, which can flow with the flue

gas, is called fly ash. Flue gas , after leaving the Air pre heaters, is sent to Electrostatic

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precipitators, where fly ash is separated from flue gas and collected in number of Ash Hopper,

arranged on Electrostatic precipitators. Ash hopper size is such that it can store all the fly ach

generated in 8 Hours continuous operation of Boiler. The flue gases from the boiler are sucked

by Induced draft fans, which are arranged after ESP. From there, flue gases are sent to Chimney,

which disposes off the flue gas to atmosphere. Ash hoppers are emptied after every 8 hours. For

disposing off the ash, it is mixed with water and no. of pumps then lift and transport the ash-

water mixture, called slurry, to pre determined place called ash bund.

Turbine is used to convert heat energy to mechanical work. Turbine consists of rotors, on

which a series of moving blades are arranged, and casing on which fixed blades are arranged.

Steam admitted to turbine, is guided by fixed blades to strikes on blades on Rotor, in the form of

jet, causing rotor to rotate thus converting heat energy to mechanical energy.

Heat energy released from the combustion of coal in the boiler is given to water

circulated in it. Water is thus converted to steam, pressure of which is 140 Kg/ cm² and

temperature is 537° C.. This steam, called live steam or main steam, is sent to High Pressure

Turbine, where it is made to strike on a series of rotor blades. When it reaches at the exhaust, its

temperature and pressure drops to 330° C and 30 Kg/ cm².

Exhaust steam from HPT is sent to Reheater, arranged in the boiler, where its temperature

is again raised to 537° C, and pressure remains 30 Kg/ cm². This steam is called Reheat steam,

which is sent to another turbine called Intermediate pressure turbine. From I.P.T, steam then is

sent to low-pressure turbine. At the exhaust of LPT, steam temperature and pressure is very low,

and further work can not be extracted from it. Hence it is condensed in the condenser, maintained

at a vaccume of 750 mm Hg. The condensed water is called condensate. Conedensate Extraction

Pumps, and Feed Water Pumps are used for pumping the condessate from Condenser to Boiler

through L. P. Heaters and H. P. Heaters. In these heaters, small quantity of steam, extracted from

intermediate stages of Turbine, heat the water. When water comes out of heaters, its temperature

is 250° C which is fed in to boiler. This is called regenerative feed heating cycle. The efficiency

of power plant increases due to regenerative feed heating.

Cooling water circulated in Condenser, at temperature of 30°C absorbs the heat energy

released in condensation due to which its temperature increases to 40° C. In cooling towers, this

hot water is again cooled to a temperature of 30° C for reuse in condenser.

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. Generator consists of Copper conductors wound on Stator and a Rotor on which Electro

magnets are arranged. Rotors of all the three turbine and Generator are coupled with common

shaft. Rotation of shaft causes rotation of Generator rotor, causing the rotation of Electro

magnets. This sets up electrical voltage on stator conductors of the generator at 15 kV.

Transformer steps up this voltage to 400 kV or 220 kV or 132 kV depending on the Grid voltage

where it is connected. The electrical energy thus generated is sent to Power Grid, from where it

reaches to the consumer through Transmission and distribution system.

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BOILER AUXILERIES There are some important machines equipment for safe and efficient working of

Boiler. These machines are called Boiler auxiliaries. They are:

a) FANS:

1) Induced draft fan (I.D. Fan) 2 No. per Boiler. It induces gaseous products from furnace

and forces out through chimney. Type ND2V, Q= 230 m3/s, Pressure = 405 mm WC, KW =

1300, Speed = 740 rpm, Radial fan.

Fig: Sectional assembly of ID Fan

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2) F.D. Fan : Forced draft fan 2 Nos. per Boiler. It forces atmospheric air to furnace as

secondary air through air preheater and wind box for combustion of fuel. Type-API – 20/11,

Pressure = 408 mmWC, Q= 451m3 /s motor 900 KW, 1480 rpm, axial fan.

Fig: Sectional view of F.D. Fan

3) P.A. Fans: Primary air for Transport of coal from mill to furnace is provided by fan.

And one tap is provided to coal mill to maintain temperature at 40c. To facilitate drying of coal,

part of P.A. fan air is routed through. The P.A. fan air should maintain speed of 80 to 100 ft/sec

is fuel pipe to maintain coal is air born state to avoid chucking of coal pipes.

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P.A. Fans have narrow section impellors, and 2 to 3 times higher speeds than I.D. or F.D.

high speed fans to give high heads required for fuel firing types blades are made of high tensile

alloy steels to resist abrasion.

Fig: P.A. Fan Sectional view

4) Seal Air Fan: Seal air pressure is higher than P.A. Fan pressure. It is required for

sealing purpose of coal mills bowl input shaft, journal assembly brgs, coal feeders shaft brgs,

sprockets otherwise dust enters above area and spoil brgs & oil.

5) Scanner fan : For sensing the flame scanners are provided at all elevations of all

corners in furnace. For cooling these scanners air is provided form these fans. Boiler will trip if

these fans fails. Capacity 1200 m3/h, Pressure = 320 mm WG, Motor 3 HP, 2970 rpm.

6) Igniter Fan : For every burner one igniter is provided for igniting the burner for

combustion & cooling igniter fan is provided. It is a centrifugal fan with backward curved.

Capacity 9000 m3/h, 75 mm WC, 1500 rpm.

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b) COAL FEEDER:

Coal comes from CHP to bunkers and coal feeder feed to any coal mill is

regulated by a coal feeder by changing its speed. Coal feeder handles crushed coal of size 15 to

25 mm. There are two types of coal feeder:

1) Gravitic Feeder: can be to a large bunker outlet there by minimizing chokage

during rainy season. Type R600

2) Volumetric type is Rotary type 100, Capacity 7.4 to 43.6 T/hr., Speed 2.7 to 16

rpm. Coal can be measured by volume of sector rotating/min.

c) COAL MILLS: Coal from feeder comes to mill & coal is crushed in the mill to the

required fineness 75% by 200 mesh. There are classifier gate through which correct size

coal only passes other coal comes back for grinding again. Mill temp. to be maintained

below comes back for grinding again. Mill temp to be maintained below 900C. the

required air flow is 50 T/h to lift the coal to furnace.

d) AIR PRE-HEATER: Air heater is unique among Boiler auxiliaries with principle purpose

of saving energy and an in come producing asset. It can have significant impact on plant

capacity and heat rate increases by 8 to 12%, saves fuel It provides heated air for drying

and conveying P.F. coal provides heated air to combustion of fuel & lower

emissionTrisector type Air heater is used in ktps. In this Flue gas flows through 180 of

portion;F.D. air flows through 128 of porsion;P.A. Fan air flows through 52 of poison

P.A. partial air is bypassed as cold air.

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e) CLINKER GRINDER:

Capacity 60 T/hr. It reduces clinkers size upto 25 to 50 mm for early transmission

through pipes to ash yard/slurry pump house. Grinder made of manganese steel.

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BOILER LIGHT-UP PROCEDURE

1. Line clear

Conform that thers is no work permit is pending and normalization of equipment after

cancellation of permit.

2. Starting of equipment

i. control& power supply made ready.

ii. Protection and interlocks are ok

iii. Normalization of equipment ( Ready to start position )

iv. Lubrication & cooling systems are in service.

Start equipment with no load & raise the load simultaneously

So as to avoid overloading the prime mover.

3. Filling up the Boiler

i. keep all the verts open & fill through all the circuits such as that no air pocket is

formed and water level in drum in the range of 40 to 50 %.

ii. To conform the level from direct gauge glass.

iii. Confirm their is sufficient water level in dearator.

4. Oil firing equipment

i. check that oil guns are insert in retracted position.

ii. Ensure that all manual valves opened and remote control valves are close.

iii. Gun tips are clean.

5. Pulverizer

i. pulverizedischange valve is open. Hot air & control damper is closed.

ii. Cold air gate is opened at 15%

6. Fans / air heater –

Normalize the damper position. Ignitorfan , scanner air fan & mill seal air fans are to be kept

on start up position.

7. Soot blowers :

check all soot blowers are in retracted position.

8. Valves in boiler

i. Keep vent valves open.

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ii. Keep drain valves & open ( expect drum , water wall &economiser)

iii. Economiser recirculation valve open condition.

9. Start regenerative air heaters.

10. Start one air cycle ( ID& FD )and adjust draft to – 10 mmwc. Adjust the corresponding

dampers in air & gas circuit

a) place the steam coil air heater in sevice.

b) Start ignitor fan ,scanner fan and seal air fans.

c) put the secondary air damper control on auto.

d) The wind box to furnace differential pressure will be maintained to 40mmwG by

adjusting auxiliary air dampers.

e) Initiate furnace purge circuit.

f) Furnace purge will take 5 minutes

11. Intitate a light up sequence of the lower elevation of ignitors and warm oil guns. Check the

combustion and adjust the air dampers. If required.

12. Maintain furnace draft by controlling the ID fan loading place furnace draft system on auto.

13. Maintain the boiler drum level by opening blowdown. Initially water level will raise.

14. Increase firing rate . Firing rate should be controlled so that furnace exit gas temperature

does not exceed 5400 c, till sufficient steam flow through superheaters and reheaters are

established.

15. Soot blow the regerative air heater with steam /compressed air to avoid plugging and

possibility of fire.

16. Close drum vent when pressure reaches to 2 to 5 kg/cm2 close the drains and vents of

reheater, which are open to atmospher before pulling vacuum in condenser

17. Close drains and vents of superheater system.

18. Increase the firing rate as required to raise the pressure, when sufficient flow through

superheaters and rcheater is established ,with the help of HP-LP by pass. The firing rate need not

be restricted to furnace outlet temperature of 5400 c

19. As the drum pressure increase , progressively throttle superheat outlet header drain &

startup vents.

20. Steam to turbine rolling is permitted as soon as the minimum permissible pressure &

temperature for the corresponding turbine metal temp.

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21. After synchronizing of T – G, close all drains & vents of boiler .

22. Increase firing rate and adjust air as per requirment.

23. Start coal firing as per requirement of loading of turbine.

24. When boiler reaches 30% of full load , the wind box to furnace differential is damped to

about 100 mmwG.

25. The oil support and igniters can be withdrawn when two adjutants coal elevation ,are in

service with atleast 50% of loading.

26. Take second air cycle in service & further load the coal firing

27. To control temperature desuperheters can be charged if required.