Date post: | 05-Apr-2018 |
Category: |
Documents |
Upload: | namit-rastogi |
View: | 227 times |
Download: | 1 times |
of 97
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
1/97
SUBMITTED BY: ALOK KUMARBRANCH: MECHANICAL ENGG.(BE 2nd YR. )
COLLEGE OF TECHNOLOGY & ENGG,UDAIPUR MPUAT UNIVERSITYUDAIPUR(RAJASTHAN)
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
2/97
ACKNOWLEDGEMENT
I would like to thankN.T.PC. BADARPURfor providing me agolden opportunity to work with them . The support and theenvironment provided to me during my project was morethan what anyone would have expected.
I am very grateful to Mr. MAN MOHAN SINGH(DY.
MANAGER) who granted me the opportunity of working as asummer trainee at mechanical Division.
I would also like to thanks Mrs RACHNA BHAL (H.R.) ,Mr. G.D SHARMA(TRAINING COORDINATOR) and myinstructors ofB.M.D.,P.A.M., T.M.D. and divisions withoutthem I would not be able to perform such a delightful job.
And at last I would like to thanks all the people
involve in the training who helped me in accomplishing it insuch a wonderful way.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
3/97
PREFACE
NTPC is one of the most important industry for producingthe electricity.Every 3rd ball in india is glown by NTPC. Thereare various divisions in NTPC for various branches likemechanical division, electrical division etc. The main
objective of preparing this report has been to present theoperations of BMD, PAM, TMD of mechanical division in alogical, innovative and lucide manner. The basic theorypresented in this report has been evolved out of simple andreadily understood principles. A sincere effort has beenmade to maintain physical concepts in various operations.
An effort has been made to give a balancedpresentation of this report with the help of figures, differenttypes of data and related suitable theories as well asconcepts.
Eventually, again I would like to thank BTPS.
ALOK KUMARBE 2ND YEAR
Email:[email protected]
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
4/97
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
5/97
* CONTENTS
*
ABOUT N.T.P.C
(NATIONAL THERMAL POWERCORPORATION)
INTRODUCTION
VISION, MISSION AND CORE VALUES
POWER PLANT OPERATIONS OPERATIONAL PERFORMANCES
CAPACITY
COAL STATION
GAS STATION
CAPTIVE POWER PLANT
POWER STATIONS IN INDIA
ABOUT B.T.P.S(BADARPUR THERMAL POWER STATION)
INTRODUCTION
TRASFORMATION OF ENERGY
COAL CYCLE
COAL TO ELECTRICITY
BASIC POWER PLANT CYCLE
ABOUT BMD(BOILER MAINTENANCE DEPARTMENT)
BOILER DESCRIPTION
FEED WATER & CONDENSATE CYCLE COMBUSTION PRINCIPLE(TRIPLE TS)
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
6/97
FURNACE & THEIR TYPE
BASICS OF FAN & DRAFT SYSTEM
PULVERISER(COAL IN TO PULVERISED COALOUT )
BOILER AUXILIARIES AND MOUNTINGS
ABOUT PAM(PLANT AUXILIARY MAINTENANCE
DEPARTMENT) THEORY OF CIRCULATION OF WATER
ASH HANDLING PLANT
CSP HOUSE
WATER TREATMENT PLANT
ABOUT TMD
(TURBINE MAINTENANCE DEPARTMENT)
STEAM TURBINE THEORY
STEAM CYCLE
TURBINE CLASSIFICATION TURBINE CYCLE
DESCRIPTION OF MAIN TURBINE
TURBINE AUXILLIARIES AN THEIRARRANGEMENT
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
7/97
http://en.wikipedia.org/wiki/Image:Ntpc.jpg7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
8/97
Type Public
Founded 1975Headquarters Delhi,India
Key peopleR S Sharma, Chairman& Managing Director
Industry Electricity generation
Products Electricity
RevenueINR 261 billion (2006)
or USD 5.91 billionNet income
INR 5.8 billion (2006)or USD 131 million
Employees 23867 (2006)
Website http://www.ntpc.co.in
BRIEFING NTPC
National Thermal Power Corporation is the largest powergeneration company in India. Forbes Global 2000 for 2008
ranked it 411th in the world. It is an Indianpublic sectorcompany
listed on the Bombay Stock Exchange although at present the
Government of India holds 89.5% of its equity. NTPC was
established as a public sector power utility by Government of
http://en.wikipedia.org/wiki/Category:Types_of_companieshttp://en.wikipedia.org/wiki/Public_companyhttp://en.wikipedia.org/wiki/1975http://en.wikipedia.org/wiki/Delhihttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Electricity_generationhttp://en.wikipedia.org/wiki/Product_(business)http://en.wikipedia.org/wiki/Revenuehttp://en.wikipedia.org/wiki/Rs.http://en.wikipedia.org/wiki/2006http://en.wikipedia.org/wiki/USDhttp://en.wikipedia.org/wiki/Net_incomehttp://en.wikipedia.org/wiki/Rs.http://en.wikipedia.org/wiki/2006http://en.wikipedia.org/wiki/USDhttp://en.wikipedia.org/wiki/Employmenthttp://en.wikipedia.org/wiki/2006http://en.wikipedia.org/wiki/Websitehttp://www.ntpc.co.in/http://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Forbes_Global_2000http://en.wikipedia.org/wiki/Public_sectorhttp://en.wikipedia.org/wiki/Bombay_Stock_Exchangehttp://en.wikipedia.org/wiki/Image:Ntpc.jpghttp://en.wikipedia.org/wiki/Category:Types_of_companieshttp://en.wikipedia.org/wiki/Public_companyhttp://en.wikipedia.org/wiki/1975http://en.wikipedia.org/wiki/Delhihttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Electricity_generationhttp://en.wikipedia.org/wiki/Product_(business)http://en.wikipedia.org/wiki/Revenuehttp://en.wikipedia.org/wiki/Rs.http://en.wikipedia.org/wiki/2006http://en.wikipedia.org/wiki/USDhttp://en.wikipedia.org/wiki/Net_incomehttp://en.wikipedia.org/wiki/Rs.http://en.wikipedia.org/wiki/2006http://en.wikipedia.org/wiki/USDhttp://en.wikipedia.org/wiki/Employmenthttp://en.wikipedia.org/wiki/2006http://en.wikipedia.org/wiki/Websitehttp://www.ntpc.co.in/http://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Forbes_Global_2000http://en.wikipedia.org/wiki/Public_sectorhttp://en.wikipedia.org/wiki/Bombay_Stock_Exchange7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
9/97
India on November 7, 1975. The reason NTPC was created was to
bridge the huge electricity supply-demand gap and the State
Electricity Boards were not able to cope up with the situation. True
to the expectation, it played a key role in the development of the
sector, lighting every fourth bulb in the country, become the largestpower utility of India, Sixth largest thermal power generator in the
World and the Second most efficient utility in terms of capacity
utilization. Rightly, NTPC has set for itself the Vision statement
To be one of the worlds largest and best power utilities,
powering Indias growth.
Vision
To be a catalyst in development of wholesale power market in India enabling
trading operation.
Mission
Provide good value to potential sellers and develop commercial arrangements . Enable NTPC to maintain optimal generation level through mutually beneficial trading.
Provide viable alternatives to buyers for meeting their demands.
Plan and establish a Power Exchange at National Level using state-of-the-art technology
Our Core Values (BCOMIT)
Business Ethics
Customer Focus
Organizational & Professional Pride
Mutual Respect and Trust
Innovation & Speed
Total Quality for Excellence
INSTALLED CAPACITY
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
10/97
NTPC Owned
15 COAL Based Plants 23,395 MW
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
11/97
07 GAS/LIQ. FUEL Based Plants 3,955MW
Owned by JVCs
3 Coal Based JVC Plants 314* MW (* Captive Power
Plant under JV with SAIL)
GRAND TOTAL
27,904 MW
COAL STATIONS
Total - 22,895 MW
# Power Plant StateCommissioned
Capacity (MW)
1 Singrauli Uttar Pradesh 2,000
2 Korba Chattishgarh 2,100
4 Farakka West Bengal 1,600
5 VindhyachalMadhya
Pradesh3,260
6 Rihand Uttar Pradesh 2,000
http://en.wikipedia.org/wiki/Singraulihttp://en.wikipedia.org/wiki/Uttar_Pradeshhttp://en.wikipedia.org/wiki/Korba%2C_Chhattisgarhhttp://en.wikipedia.org/wiki/West_Bengalhttp://en.wikipedia.org/wiki/Singraulihttp://en.wikipedia.org/wiki/Uttar_Pradeshhttp://en.wikipedia.org/wiki/Korba%2C_Chhattisgarhhttp://en.wikipedia.org/wiki/West_Bengal7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
12/97
7 Kahalgaon Bihar 1340
8 NCTPPDadri Uttar Pradesh 840
9Talcher
KanihaOrissa 3000
10 Unchahar Utter Pradesh 1050
11Talcher
AngulOrissa 460
12 Simhadri AndhraPradesh 1,000
13 Tanda Uttar Pradesh 440
14 Badarpur Delhi 705
15 Sipat-II Chattishgarh 500
GAS/LIQ. FUEL STATIONS
http://en.wikipedia.org/wiki/Biharhttp://en.wikipedia.org/wiki/Orissahttp://en.wikipedia.org/wiki/Biharhttp://en.wikipedia.org/wiki/Orissa7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
13/97
Total - 3955 MW
#Power Plant State Commissioned Capacity (MW)
1
6Anta Rajasthan 413
1
7Auraiya Uttar Pradesh 652
1
8Kawas Gujrat 645
1
9Dadri Uttar Pradesh 817
2
0Jhanor-Gandhar Gujrat 648
2
1 Kayamkulam Kerala 350
2
2Faridabad Haryana 430
http://en.wikipedia.org/wiki/Rajasthanhttp://en.wikipedia.org/wiki/Uttar_Pradeshhttp://en.wikipedia.org/wiki/Gujrathttp://en.wikipedia.org/wiki/Keralahttp://en.wikipedia.org/wiki/Rajasthanhttp://en.wikipedia.org/wiki/Uttar_Pradeshhttp://en.wikipedia.org/wiki/Gujrathttp://en.wikipedia.org/wiki/Kerala7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
14/97
CAPATIVE POWER PLANT UNDER JV WITH SAIL& GAIL
Total - 1054 MW
# Power Plant StateCommissioned Capacity
(MW)
23
Durgapur West Bengal 120
2
4Rourkela Orissa 120
2
5 Bhilai Chattishgarh 74
2
6
Ratnagiri Gas Power
Plant LimitedMaharashtra 740
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
15/97
CAPACITY ADDITION
Additional capacity under implementation in 10'thFive Year Plan (2002-2007)
# Power Plant StateCapacity
(MW)
Projected
Commissioning
Date
1 Unchahar Stage-3Uttar
Pradesh210 Sept 2006
2Kahalgaon Phase-2
(Stage-1) Unit-5Bihar 500 Nov 2006
3Vindhyachal Stage-3
Unit-9
Madhya
Pradesh500 July 2006
4Kahalgaon Phase-2
(Stage-2) Unit-7Bihar 500 Mar 2007
5Kahalgaon Phase-2
(Stage-1) Unit-6Bihar 500 May 2007
6 Sipat Stage-2 Unit-1 Chattishgarh 500 Jun 2007
http://en.wikipedia.org/wiki/Five-Year_Plans_of_Indiahttp://en.wikipedia.org/wiki/Five-Year_Plans_of_India7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
16/97
7Bhilai (JV with SAIL)
Unit-1Chattishgarh 250 Jul 2007
8Vindhyachal Stage-3
Unit-10
Madhya
Pradesh500 Mar 2007
9Bhilai (JV with SAIL)
Unit-2Chattishgarh 250 Oct 2007
1
0 Sipat Stage-2 Unit-2 Chattishgarh 500 Dec 2007
Total4710
MW
UPCOMING/FUTURE PROJECTS
In November 2007, NTPC signed a joint venture withIndian Railways to set up a 1,000 Mega Watt (MW) power plant in
Nabinagar in Bihar. The JV would be called Bharatiya Rail Bijlee
Company.
http://en.wikipedia.org/wiki/Indian_Railwayshttp://en.wikipedia.org/wiki/Indian_Railways7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
17/97
NTPC POWER STATIONS IN INDIA
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
18/97
DESCRIPTIONN OF BTPS
(BADARPUR THERMAL POWER STATION)
Address: Badarpur,New Delhi 110 044
Telephone: (STD-011) - 26949523
Fax: 26949532
Email:
Installed Capacity 720 MW
Derated Capacity 705 MW
Location New DelhiCoal Source Jharia Coal Fields
Water Source Agra Canal
Beneficiary States Delhi
Unit Sizes
3X95 MW
2X210 MW
Units Commissioned
Unit I- 95 MW - July 1973
Unit II- 95 MW August 1974Unit III- 95 MW March 1975
Unit IV - 210 MW December 1978
Unit V - 210 MW - December 1981
Transfer of BTPS to
NTPC
Ownership of BTPS was transferred to
NTPC with effect from 01.06.2006
through GOIs Gazette Notification.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
19/97
COAL TO ELECTRICITY TRANSFORMATION OF ENERGY
COAL BOILER STEAM TURBINEChemical energy Thermal energy Mechanical energy
DIFFERENT LOADS GENERATORLight energy or other required energy Electrical energy
CHP(COAL HANDALING DEPARTMENT)
OR(COAL CYCLE)
From Jharia mines
Railway wagon
BTPS wagon tripper
Magnetic separator
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
20/97
Crusher house
Coal stock yard
RC bunker
RC feeder
Bowl mill
Furnace Basic Power Plant Cycle
The thermal (steam) power plant uses a dual(vapour + liquid) phase cycle. It is a closed cycle to enablethe working fluid (water) to be used again and again. Thecycle used is "Rankine Cycle" modified to include superheating of steam, regenerative feed water heating and
reheating of steam.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
21/97
On large turbines, it becomes economical toincrease the cycle efficiency by using reheat, which is a wayof partially overcoming temperature limitations. Byreturning partially expanded steam, to a reheat, the averagetemperature at which heat is added, is increased and, byexpanding this reheated steam to the remaining stages of theturbine, the exhaust wetness is considerably less than itwould otherwise be conversely, if the maximum tolerablewetness is allowed, the initial pressure of the steam can beappreciably increased.
Coal to Steam
Coal from the coal wagons is unloaded in the coalhandling plant. This Coal is transported up to the raw coalbunkers with the help of belt conveyors. Coal is transportedto Bowl Mills by Coal feeders The coal is pulverized in the
Bowl Mill, where it is ground to a powder form. The millconsists of a round metallic table on which coal particles fall.This table is rotated with the help of a motor. There are threelarge steel rollers which are spaced 120" apart. When there isno coal, these rollers does not rotate but when the coal is fedto the table it packs up between roller and the table and this
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
22/97
forces the rollers to rotate. Coal is crushed by the crushingaction between the rollers and rotating table. This crushedcoal is taken away to the furnace through coal pipes with thehelp of hot and cold air mixture from P.A. Fan.
Water from the boiler feed pump passes througheconomizer and reaches the boiler drum. Water from thedrum passes through down comers and goes to bottom ringheader. Water from the bottom ring header is divided to all
the four sides of the furnace. Due to heat and- the densitydifference the water rises up in the water wall tubes . "Wateris partly converted to steam 'as it rises up in the furnace. Thissteam and water mixture is again taken to the boiler drumwhere the steam is separated from water. Water follows thesame path while the steam is sent to superheaters for
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
23/97
superheating. The superheaters are located inside thefurnace and the steam is superheated (540"C) and finally itgoes to turbine.Steam to mechanical Power
From the boiler, a steam pipe conveys steam to theturbine through a stop valve (which can be used to. shut offsteam in an emergency) and through control valves thatautomatically regulate the supply of steam to the turbinewhere it passes through a ring of stationary blades fixed tothe cylinder wall. These act as nozzles and direct the steaminto a second ring of moving blades mounted on a disc
which rotates the blades and its passage of some heat energyis changed into mechanichal energy.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
24/97
The turbine shaft usually rotates at 3,000revolutions per minute. This speed is determined by thefrequency of the electrical system used in this country and isthe speed at which a 2- pole generator must be driven togenerate alternating current at a frequency of 50 cycles persecond.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
25/97
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
26/97
BOILER
DESCRIPTION:
A boiler is a closed vessel in which waterorotherfluid is heated. The heated or vaporized fluid exits the boiler
for use in various processes or heating applications
Construction of boilers is mainly of
steel, stainless steel, and wrought iron. In live steam models,
copperorbrass is often used. Historically copper was often used
for fireboxes (particularly for steam locomotives), because of its
http://en.wikipedia.org/wiki/Pressure_vesselhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Mild_steelhttp://en.wikipedia.org/wiki/Stainless_steelhttp://en.wikipedia.org/wiki/Wrought_ironhttp://en.wikipedia.org/wiki/Live_steamhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Brasshttp://en.wikipedia.org/wiki/Fireboxhttp://en.wikipedia.org/wiki/Steam_locomotivehttp://en.wikipedia.org/wiki/Pressure_vesselhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Mild_steelhttp://en.wikipedia.org/wiki/Stainless_steelhttp://en.wikipedia.org/wiki/Wrought_ironhttp://en.wikipedia.org/wiki/Live_steamhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Brasshttp://en.wikipedia.org/wiki/Fireboxhttp://en.wikipedia.org/wiki/Steam_locomotive7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
27/97
better thermal conductivity. The price of copper now makes this
impractical.
Cast iron is used for domestic water heaters. Although
these are usually termed "boilers", their purpose is to produce hot
water, not steam, and so they run at low pressure and try to avoidactual boiling. The brittleness of cast iron makes it impractical for
steam pressure vessels.
The steam generating boiler has to produce steam at
the high purity, pressure and temperature required for the steam
turbine that drives the electrical generator. The boiler includes the
economizer, the steam drum, the chemical dosing equipment, and
http://en.wikipedia.org/wiki/Cast_ironhttp://en.wikipedia.org/wiki/Cast_iron7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
28/97
the furnace with its steam generating tubes and the superheater
coils. Necessary safety valves are located at suitable points to
avoid excessive boiler pressure. The air and flue gas path
equipment include: forced draft (FD) fan, air preheater (APH),
boiler furnace, induced draft (ID) fan, fly ash collectors(electrostatic precipitatororbaghouse) and the flue gas stack.[1][2]
[3]
Schematic diagram of typical coal-fired power plant steam generator highlighting the
air preheater (APH) location.
MAIN BOILER: AT 100% LOAD
Evaporation 700t/hr
Feed watertemperature 247C
Feed waterleaving economizer 276C
http://en.wikipedia.org/wiki/Furnacehttp://en.wikipedia.org/wiki/Flue_gashttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Electrostatic_precipitatorhttp://en.wikipedia.org/wiki/Dust_collector#Fabric_filtershttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/Thermal_power_station#cite_note-0%23cite_note-0http://en.wikipedia.org/wiki/Thermal_power_station#cite_note-Babcock-1%23cite_note-Babcock-1http://en.wikipedia.org/wiki/Thermal_power_station#cite_note-Elliott-2%23cite_note-Elliott-2http://en.wikipedia.org/wiki/Image:Steam_Generator.pnghttp://en.wikipedia.org/wiki/Image:Steam_Generator.pnghttp://en.wikipedia.org/wiki/Image:Steam_Generator.pnghttp://en.wikipedia.org/wiki/Furnacehttp://en.wikipedia.org/wiki/Flue_gashttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Electrostatic_precipitatorhttp://en.wikipedia.org/wiki/Dust_collector#Fabric_filtershttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/Thermal_power_station#cite_note-0%23cite_note-0http://en.wikipedia.org/wiki/Thermal_power_station#cite_note-Babcock-1%23cite_note-Babcock-1http://en.wikipedia.org/wiki/Thermal_power_station#cite_note-Elliott-2%23cite_note-Elliott-27/31/2019 Summer Training Project Report of Ntpc on Mech Engg
29/97
STEAM TEMPERATURE:
Drum 341C
Super heater outlet 540C
Reheat inlet 332C
Reheat outlet 540C
STEAM PRESSURE:
Drum design 158.20 kg/cm2
Drum operating 149.70 kg/cm2
Super heater outlet 137.00 kg/cm2
Reheat inlet 26.35 kg/cm2
Reheat outlet 24.50 kg/cm2
FUEL:
COAL DESIGN WORST
Fixed carbon 38% 25%
Volatile matter 26% 25%
Moisture 8% 9%
Grindability 50% Hardgrove 45% Hardgrove
OIL:
Calorific value of fuel oil 10,000 kcal/kg
Sulphur content 4.5% W/W
Moisture content 1.1% W/W
Flash point 66C
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
30/97
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
31/97
FEED WATER CYCLE
Deaerator
Boiler feed pump
H.P. Heater-1
H.P.Heater-2
H.P. Heater-3
Feed water line
Economiser
Boiler drum
Downcomer
Water walls
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
32/97
Condensate Cycle
From low pressure turbine
Condenser
Condensate pump
Ejector
Gland steam cooler
GSC2
LPH2
LPH3
LPH4
Deareator
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
33/97
Principles of Combustion
The primary function of oil and coal burning systems the
process of steam generation is to provide controlled efficientconversation of the chemical energy of the fuel into heat energy
which is then transferred to the heat absorbing surfaces of the
steam generator. The combustion elements of a fuel consist of
carbon, hydrogen and usually a small amount of sulphur. When
combustion is properly completed the exhaust gases will contain,
carbon dioxide,. water vapour, sulphur dioxide and a large volume
of Nitrogen, Combustion is brought about by combining carbon
and hydrogen or hydrocarbons with the oxygen in air. Whencarbon burns completely, it results in the formation of a gas known
as carbon dioxide. When carbon burns incompletely it forms
carbon monoxide.
The following factors in efficient combustion areusually referred to as "The three Ts
Time:
It will take a definite time to heat the fuel to its ignition
temperature and having ignited, it will also take time to bum.
Consequently sufficient time must be allowed for complete
combustion of the fuel to take place in the chamber.
Temperature:
A fuel will not burn until it has reached its
ignition temperature. The speed at which this Temperature will be
reached is increased by preheating the combustion air. The
temperature of the flame of the burning fuel may vary with the
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
34/97
quantity of air used. Too much combustion air will lower the flame
temperature and may cause unstable ignition.
Turbulence:
Turbulence is introduced to achieve a rapid
relative motion between the air and the fuel particles. It is found
that this produces a quick propagation of the flame and its rapid
spread throughout the fuel/air mixture in the combustion chamber.
Combustion efficiency: It varies with individual different grades of
fuel within each boiler. The idea to be aimed at is the correct
quantity of air together with good mixing of fuel and air to obtain
the maximum heat release.
Maximum combustion efficiency depends on
Design of the boiler.
Fuel used.
Skill in obtaining combustion with the minimum amount of
excess air.
FURNACE
INTRODUCTION:
Furnace is primary part of boiler where the
chemical energy of fuel is converted to thermal energy by
combustion. Furnace is designed for efficient and complete
combustion. Major factors that assist for efficient combustion are
amount of fuel inside the furnace and turbulence, which causes
rapid mixing between fuel and air. In modern boilers, water-cooled
furnaces are used.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
35/97
TYPES OF FURNACE
P.F. FIRED DRY BOTTOM FURNACE:
The tall rectangular radiant type furnace has now become afeature of modern dry bottom P.F. boiler. Indorsed height not only
facilitates adequate natural circulation but also aids reduction of
furnace exit gas temperature and hence less soot deposit in
superheaters and reheaters. SLAG TYPE FURNACE:
Furnace of this type normally has two parts. Primary
furnace is used for very high rate of combustion. Provision is tomake molten slag and crush the granular form for easy disposal. As
the ash has to flow from the primary furnace, coal having low
melting temperature can only be used. To obtain high temperature
inside the primary surface that will facilitate the easy flow of ash,
very small but highly rated design is needed for primary furnace
hence maintenance is needed.
OIL FIRED BOILER FURNACE:
Normally about 65% of furnace volume is enough for an
oil-fired boiler as compared to the corresponding P.F. fired boiler.
Oil-fired furnace is generally closed at the bottom, as there is no
need to remove slag as in case of P.F. fired boiler. The bottom part
will have small amount of slope to prevent film boiler building in
the bottom tubes.
If boiler has to design for both P.F. as well as oil, the
furnace has to be designed for coal, as otherwise higher heatloading with P.F. will cause slogging and high furnace exit gas
temperature.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
36/97
SPECIFICATIONS
FURNACE
Width 13.868 m
Depth 10.592 m
Height 42.797 m
Volume 5210 m3
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
37/97
BOILER DRUM
Drum is of fusion-welded design with welded hemi-
spherical dished ends. It is provided with stubs for welding all theconnecting tubes i.e. downcomers, risers, pipes, saturated steam
outlet. The function of steam drum internals is to separate the
water from the steam generated in the furnace walls and to reduce
the dissolved solid contents of the steam below the prescribed limit
of 1 ppm and also take care of the sudden change of steam demand
for boiler.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
38/97
The secondary stage of two opposed banks of closely spaced thin
corrugated sheets, which direct the steam and force the remaining
entertained water against the corrugated plates. Since the velocity
is relatively low this water does not get picked up again but runsdown the plates and off the second stage of the two steam outlets.
From the secondary separators the steam flows upwards to the
series of screen dryers, extending in layers across the length of the
drum. These screens perform the final stage of separation.
WATER WALLS:
Water flows to the water walls from the
boiler drum by natural circulation. The front and the two side water
walls constitute the main evaporation surface absorbing the bulk of
radiant heat of the fuel burnt in the chamber. The front and rear
walls are bent at the lower ends to form a water-cooled slag
hopper. The upper part of the chamber is narrowed to achieve
perfect mixing of combustion gases. The water walls tubes are
connected to headers at the top and bottom. The rear water walls
tubes at the top are grounded in four rows at a wider pitch forming
the grid tubes.
REHEATER
Reheater is used to raise the temperature of
steam from which a part of energy has been extracted in high-
pressure turbine. This is another method of increasing the cycle
efficiency. Reheating srequires additional equipment I.e. Heatingsurface connecting boiler and turbine pipe safety equipment like
safety valve, non-return valve, isolating valves, high pressure feed
pump, etc. Reheater is composed to two sections namely front and
rear pendant section which is located above the furnace arch
between water-cooled screen wall tubes and rear wall hanger tubes.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
39/97
Super heaters
Whatever type of boiler is used, steam will
leave the water at its surface and pass into the steam space. Steamformed above the water surface in a shell boiler is always saturated
and cannot become superheated in the boiler shell, as it is
constantly in contact with the water surface.
If superheated steam is required, the saturated
steam must pass through a superheater. This is simply a heat
exchanger where additional heat is added to the saturated steam.
In water-tube boilers, the superheater may be
an additional pendant suspended in the furnace area where the hot
gases will provide the degree of superheat required (see Figure
3.4.4). In other cases, for example in CHP schemes where the gas
turbine exhaust gases are relatively cool, a separately fired
superheater may be needed to provide the additional heat.
Fig. A water tube boiler with a super heater
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
40/97
If accurate control of the degree of superheat is
required, as would be the case if the steam is to be used to drive
turbines, then an attemperator (desuperheater) is fitted. This is a
device installed after the superheater, which injects water into the
superheated steam to reduce its temperature.
ECONOMISER
The function of an economizer in a steam
generating unit is to absorb heat from the flue gases and add as a
sensible heat to the feed-water before the water enters the
evaporation circuit of the boiler.Earlier economizer were introduced mainly to recover the
heat available in flue gases that leaves the boiler and provision of
this addition heating surface increases the efficiency of steam
generators. In the modern boilers used for power generation feed-
water heaters were used to increase the efficiency of turbine unit
and feed-water temperature.
LOCATION AND MAINTENANCE:
It is usual to locate economizer ahead of air
heater. Counter flow arrangement is normally selected so that
heating surface requirement is kept minimum for the same
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
41/97
temperature drop in flue gas. Water flow is from bottom to top so
that steam if any formed during the heat transfer can move along
with water and the lock up steam which will cause overheating and
failure of economizer tube.
Manholes and adequate spacing between thebanks of tubes are provided for inspection and maintenance works.
AIR PREHEATER
Air preheater absorbs waste
heat from the flue gases and transfers this heat to incoming cold
air, by means of continuously rotating heat transfer element ofspecially formed metal plates. Thousands of these high efficiency
elements are spaced and compactly arranged within 12 sections.
Sloped compartments of a radially divided cylindrical shell called
the rotor. The housing surrounding the rotor is provided with duct
connecting both the ends and is adequately scaled by radial and
circumferential scaling. Air Preheater consists of:
Connecting plates
Housing
Rotor
Heating surface elements
Bearings
Sector plates and Sealing arrangement
SPECIFICATIONS
Number of air preheater per unit 2
Heater size 27-VI-(T)-74 casing
Approx heating surface 19000 m2 each
Rotor drive motor 15 H.P.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
42/97
Speed reduction ratio 110:1
Approx oil capacity 13 Gallons
Solenoid Value 110 V, A.C.
Basics of Fans
The air we need for combustion in the furnace and the flue gas that
we must evacuate would not possible without using fans. A fan iscapable of imparting energy to the air/gas in the form of a boost in
pressure. We overcome the losses through the system by means of
this pressure boost. The boost is dependent on density for a given
fan at a given speed. The higher the temperature, the lower is the
boost. Fan performance (Max. capability) is represented as volume
vs. pressure boost.
The basic information needed to select a fan is:
Air or Gas flow (Kg/hr).
Density (function of temperature and pressure).
System, resistance (losses).
Classification of FansIn boiler practice, we meet the following types of fans.
Axial fans
Centrifugal (Radial) fansAxial FansIn this type the movement of air or gas is parallel to its exit of
rotation. These fans are better suited to low resistance applications.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
43/97
The axial flow fan uses the screw like action of a multiplied
rotating shaft, or propeller, to move air or gas in a straight through
path.
Centrifugal Fan
This fan moves gas or air perpendicular to
the axis of rotation. There are advantages when the air must be
moved in a system where the frictional resistance is relatively high.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
44/97
The blade wheel whirls air centrifugally between each pair of
blades and forces it out peripherally at high velocity and high static
pressure. More air is sucked in at the eye of the impeller. As the air
leaves the revolving blade tips, part of its velocity is converted into
additional static pressure by scroll shaped housing.
There are three types of blades.
Backward curved blades.
Forward curved blades.
Radial blades.
Draft SystemBefore a detailed study of industrial fans it is in the fitness of
things to understand the various draft systems maintained by those
fans.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
45/97
The terms draft denotes the difference
between the atmospheric pressure and the pressure existing in the
furnace.
Depending upon the draft used, we have
Natural Draft
Induced Draft
Forced Draft
Balanced Draft System
Natural Draft
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
46/97
In natural draft units the pressure
differentials are obtained have constructing tall chimneys so that
vacuum is' created in the furnace Due to small pressure difference,
air is admitted into the furnace.
Induced Draft
In this system the air is admitted to natural
pressure difference and the flue gases are taken out by means of
induced Draft fans and the furnace is maintained under vacuum.Forced Draft
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
47/97
A set of forced draft fans are made use of forsupplying air to the furnace and so the furnace is pressurized. The
flue gases are taken out due to the pressure difference between the
furnace and the atmosphere.
Balance Draft
Here a set of Induced and Forced Draft
Fans are utilized in maintaining a vacuuming the furnace.
Normally all the power stations utilize this draft system.
Industrial Fans
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
48/97
I.D. Fan
The induced Draft Fans are generally of
Axial -Impulse Type. Impeller nominal diameter is of the order of
2500 mm.
The fan consists of the following sub-assemblies
Suction Chamber
Inlet Vane Control
Impeller
Outlet Guide Vane Assembly
The outlet guides are fixed in between the
case of the diffuser and the casing. These guide vanes serve to
direct the flow axially and to stabilize the draft-flow caused in the
impeller. These outlet blades are removable type from outside.
During operation of the fan itself these blades can be replaced one
by one.
Periodically the outlet blades can be removed one at a time to find
out the extent of wear on the blade. If excessive wear is noticed the
blade can be replaced by a new blade.F.D Fan
The fan, normally of the same type as ID Fan, consists of the
following components:
* Silencer
* Inlet bend
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
49/97
* Fan housing
* Impeller with blades and setting mechanism
* Guide wheel casing with guide vanes and diffuser.
The centrifugal and setting forces of the blades are taken up by the
blade bearings. The blade shafts are placed in combined radial and
axial antifriction bearings which are sealed off to the outside. The
angle of-incidence of the blades may be adjusted during operation.
The characteristic pressure volume curves of the fan may be
changed in a large range without essentially modifying the
efficiency. The fan can then be easily adapted to changing
operating conditions.
The rotor is accommodated in cylindrical roller bearings and aninclined ball bearing at the drive side adsorbs the axial thrust.
Lubrication and cooling these bearings is assured by a combined
oil level and circulating lubrication system.
Primary Air FanP.A. ran if flange mounted design, single stage suction, NDFV
type, backward curved bladed radial fan operating on the principle
of energy transformation due to centrifugal forces. Some amountof the velocity energy is converted to pressure energy in the spiral
casing. The fan is driven at a constant speed and the flow is
controlled by varying the angle of the inlet vane control. The
Special feature of the fan is that is provided with inlet guide vane
control with a positive and precise link mechanism.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
50/97
PulverizerA pulverizer is a mechanical device for the grinding of many
different types of materials. For example, they are used to
pulverize coal for combustion in the steam-generating furnaces of
fossil fuel power plants.
Fig. PULVERIZER
http://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Furnaceshttp://en.wikipedia.org/wiki/Fossil_fuel_power_planthttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Furnaceshttp://en.wikipedia.org/wiki/Fossil_fuel_power_plant7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
51/97
Types of Pulverizers
Ball and Tube Mills
A ball mill is a pulverizer that consists of a
horizontal rotating cylinder, up to three diameters in length,
containing a charge of tumbling or cascading steel balls, pebbles,
or rods.
A tube mill is a revolving cylinder of up to five
diameters in length used for fine pulverization of ore, rock, and
other such materials; the material, mixed with water, is fed into the
chamber from one end, and passes out the other end as slime.
Ring and Ball Mill
This type of mill consists of two rings separated
by a series of large balls. The lower ring rotates, while the upper
ring presses down on the balls via a set of spring and adjuster
assemblies. The material to be pulverized is introduced into the
center or side of the pulverizer (depending on the design) and is
ground as the lower ring rotates causing the balls to orbit between
the upper and lower rings. The pulverized material is carried out of
the mill by the flow of air moving through it. The size of the
pulverized particles released from the grinding section of the mill
is determined by a classifer separator.
MPS Mill
Similar to the Ring and Ball Mill, this mill useslarge "tires" to crush the coal. These are usually found in utility
plants.
Bowl Mill
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
52/97
Similar to the MPS mill, it also uses tires to crush coal. There are
two types, a deep bowl mill, and a shallow bowl mill.Advantage of pulverized coal
Efficient utilization of cheap and low grade coal
Flexibility to meet fluctuating load
Elevation of bending loser Boiler Fittings and Mountings Safety valve
A safety valve is a valve mechanism for the automatic
release of a gas from a boiler, pressure vessel, or other system
when the pressure or temperature exceeds preset limits. It is part of
a bigger set named Pressure Safety Valves (PSV) or Pressure
Relief Valves (PRV). The other parts of the set are named reliefvalves, safety relief valves, pilot-operated safety relief valves, low
pressure safety valves, vacuum pressure safety valves.
Function and design
Fig. Boiler safety valve
Boiler stop valves
http://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Pressure_vesselhttp://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/w/index.php?title=Pressure_Safety_Valve&action=edit&redlink=1http://en.wikipedia.org/wiki/Pressure_Relief_Valvehttp://en.wikipedia.org/wiki/Pressure_Relief_Valvehttp://en.wikipedia.org/wiki/Relief_valvehttp://en.wikipedia.org/wiki/Relief_valvehttp://en.wikipedia.org/wiki/Valvehttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Pressure_vesselhttp://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/w/index.php?title=Pressure_Safety_Valve&action=edit&redlink=1http://en.wikipedia.org/wiki/Pressure_Relief_Valvehttp://en.wikipedia.org/wiki/Pressure_Relief_Valvehttp://en.wikipedia.org/wiki/Relief_valvehttp://en.wikipedia.org/wiki/Relief_valve7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
53/97
A steam boiler must be fitted with a stop
valve (also known as a crown valve) which isolates the steam
boiler and its pressure from the process or plant. It is generally an
angle pattern globe valve of the screw-down variety
Fig: Boiler stop valve
The stop valve is not designed as a
throttling valve, and should be fully open or closed. It should
always be opened slowly to prevent any sudden rise in downstream
pressure and associated waterhammer, and to help restrict the fall
in boiler pressure and any possible associated priming.
Feedwater check valves
The feedwater check valve is
installed in the boiler feedwater line between the feedpump and
boiler. A boiler feed stop valve is fitted at the boiler shell.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
54/97
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
55/97
other pressure containers such as blowdown vessels, and will
usually have smaller dials as shown in Figure
Fig: Typical pressure gauge with ring siphon
Gauge glasses and fittings
All steam boilers are fitted with at leastone water level indicator, but those with a rating of 100 kW or
more should be fitted with two indicators. The indicators are
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
56/97
usually referred to as gauge glasses complying with BS 3463.
Fig. Gauge glass and fittings
A gauge glass shows the current level of
water in the boiler, regardless of the boiler's operating conditions.
Gauge glasses should be installed so that their lowest reading will
show the water level at 50 mm above the point where overheating
will occur. They should also be fitted with a protector around
them, but this should not hinder visibility of the water level.
Gauge glasses are prone to damage from a number of sources, suchas corrosion from the chemicals in boiler water, and erosion during
blow down, particularly at the steam end. Any sign of corrosion or
erosion indicates that a new glass is required.
When testing the gauge glass steam
connection, the water cock should be closed. When testing the
gauge glass water connections, the steam cock pipe should be
closed.
Gauge glass guards
The gauge glass guard should be kept
clean. When the guard is being cleaned in place, or removed for
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
57/97
cleaning, the gauge should be temporarily shut-off.
Make sure there is a satisfactory water
level before shutting off the gauge and take care not to touch or
knock the gauge glass. After cleaning, and when the guard hasbeen replaced, the gauge should be tested and the cocks set in the
correct position.Coal Bunker
These are in process storage silos used for
storing crushed coal from the coal handling system. Generally,
these are made up of welded steel plates.' Normally, there are six
such bunkers supplying coal of the corresponding mills. These arelocated on top of the mills so as to aid in gravity feeding of coal.
Coal FeederEach mill is provided with a drag link chain/ rotary/ gravimetric
feeder to transport raw coal from the bunker to the inlet chute,
leading to mill at a desired rate.MillsThere are six mill (25% capacity each), for every 200 .MW unit,
located adjacent to the furnace at '0' M level. These mills pulverize
coal to the desired fineness to be fed to the furnace for combustion.Electrostatic precipitator
These are generally two plate type located
between boiler and the crr1imney. The precipitator is arranged for
horizontal gas flow and is constructed with welded steel casi
**************************
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
58/97
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
59/97
WATER CIRCULATION SYSTEM
Theory of circulation
Water must flow through the heat absorption
surface of the boiler in order that it be evaporated into steam. In
drum type units (natural and controlled circulation) the water is
circulated from the drum through the generating circuits and then
back to the drum where the steam is separated and directed to the
super heater. The water leaves the drum through the down comers
at a temperature slightly below the saturation temperature. The
flow through the furnace wall is at saturation temperature. Heatabsorbed in water wall is latent heat of vaporization creating a
mixture of steam and water. The ratio of the weight of the water to
the weight of the steam in the mixture leaving the heat absorption
surface is called
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
60/97
Types of boiler circulating system:
Natural circulation system
Controlled circulation system
Combines circulation system
Natural circulation system
Water delivered to steam generator from
feed heater is at a temperature well below the saturation value
corresponding to that pressure. Entering first the economizer it isheated to about 30-40C below saturation temperature. From
economizer the water enters the drum and thus joins the circulation
system. Water entering the drum flows through the down comer
and enters ring heater at the bottom. In the water walls a part of the
water is converted to steam and the mixture flows back to the
drum. In the drum, the steam is separated, and sent to super heater
for super heating and then sent to the high pressure turbine.
Remaining water mixes with the incoming water from theeconomizer and the cycle is repeated.
The circulation in this case takes place on
the thermo-siphon principle. The dowm comers contain relatively
cold water whereas the riser tubes contain a steam water mixture.
Circulation takes place at such a rate that the driving force and the
frictional resistance in water walls are balanced.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
61/97
As the pressure increases, the difference in density between waterand steam reduces. Thus the hydrostatic head available will not be
able to overcome the frictional resistance for a flow corresponding
to the minimum requirement of cooling of water wall tubes.
Therefore natural circulation is limited to the boiler with drum
operating pressure around 175 kg/cm.
Controlled circulation system
Beyond 80 kg/cm of pressure, circulationis to be assisted with mechanical pumps to overcome the frictional
losses. To regulate the flow through various tubes, orifice plates
are used. This system is applicable in the high sub-critical regions
(200 kg/cm).
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
62/97
Combined circulation system
Beyond the critical pressure, phase
transformation is absent, and hence once through system is
adopted. However, it has been found that even at super critical
pressure, it is advantageous to recirculate the water through the
furnace tubes and simplifies the start up procedure. A typical
operating pressure for such a system is 260 kg/cm.
ASH HANDLING PLANT
The ash produced in the boiler is transported
to ash dump area by means of sluicing type hydraulic ash handling
system, which consists of Bottom ash system, Ash water system
and Ash slurry system.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
63/97
Bottom ash system
In the bottom ash system the ashdischarged from the furnace bottom is collected in two water
compounded scraper through installed below bottom ash hoppers.
The ash is continuously transported by means of the scraper chain
conveyor onto the respective clinker grinders which reduce the
lump sizes to the required fineness. The crushed ash from the
bottom ash hopper from where the ash slurry is further transported
to operation, the bottom ash can be discharged directly into the
sluice channel through the bifurcating chute bypass the grinder.The position of the flap gate in the bifurcating chute bypasses the
grinder. The position of the flap gate in the bifurcating chute is to
be manually changed.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
64/97
Fly ash system
The flushing apparatus are provided underE.P. hoppers (40 No.s), economizer hoppers (4 No.s), air pre
heaters (2 No.s), and stack hoppers (4 No.s),. The fly ash gets
mixed with flushing water and the resulting slurry drops into the
ash sluice channel. Low pressure water is applied through the
nozzle directing tangentially to the section of pipe to create
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
65/97
turbulence and proper mixing of ash with water. For the
maintenance of flushing apparatus plate valve is provided between
apparatus and connecting tube.
Ash water system
High pressure water required for bottom ash
hopper quenching nozzles, bottom ash hopper spraying, clinker
grinder sealing scraper bars, cleaning nozzles, bottom ash hopper
seal through flushing, economizer hopper flushing nozzles and
sluicing trench jetting nozzles is tapped from the high pressure
water ring mainly provided in the plant area.
Low pressure water required for bottom ash
hopper seal through make up, scraper conveyor make up, flushing
apparatus jetting nozzles for all fly ash hoppers excepting
economizer hoppers, is trapped from low pressure water rings
mainly provided in the plant area.
Ash slurry system
Bottom ash and fly ash slurry of the system
is sluiced upto ash pump along the channel with the acid of high
pressure water jets located at suitable intervals along the channel.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
66/97
Slurry pump suction line consisting of reducing elbow with drain
valve, reducer and butterfly valve and portion of slurry pumpdelivery line consisting of butterfly valve, pipe & fitting has also
been provided.
CHPH
(CONTROL STRUCTURE PUMP HOUSE)
The control system has following pumps:-
Chlorine pump-2(for chlorination of water) HP pump-6(for boiling of water)
LP pump-3(for EP pump house)
Fire pump-(incase of fire breakdown)
TWS pump-3(for screening of water)
CRW pump-3(supply water for water treatment)
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
67/97
This house is known as control house because amount of water to
be supplied for treatment is controlled from this house with the
help of these pumps. Generally 2 CRW pumps out of 3pumps
remains open.similarly,1 FS ,2 LP,4 HP,1 TWS pumps remainsopen. If more water is needed then others pumps are opened.
WATER TREATMENT PLANT
As the types of boiler are not alike their
working pressure and operating conditions vary and so do the typesand methods of water treatment. Water treatment plants used in
thermal power plants are designed to process the raw water to
water with vary lowin dissolved solids known as "dematerializedwater". No doubt, this plant has to be engineered very carefully
keeping in view the type of raw water to the thermal plant, its
treatment costs and overall economics
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
68/97
Actually, the type of demineralization processchosen for a power station depends on three main
factors:
The quality of the raw water.
The degree of de-ionization i.e. treated water quality
Selectivity of resins.
Water treatment process which is generally made up of two
sections:
Pretreatment section
Demineralization section
Pretreatment section
Pretreatment plant removes the suspended
solids such as clay, silt, organic and inorganic matter, plants and
other microscopic organism. The turbidity may be taken as of two
types of suspended solids in water. Firstly, the separable solids and
secondly the non separable solids (colloids). The coarse
components, such as sand, silt etc, can be removed from the waterby simple sedimentation. Finer particles however, will not settle in
any reasonable time and must be flocculated to produce the large
particles which are settle able. Long term ability to remain
suspended in water is basically a function of both size and specific
gravity. The settling rate of the colloidal and finely divided
(approximately 001 to 1 micron) suspended matter is so slow that
removing them from water by plain sedimentation is tank shaving
ordinary dimensions is impossible. Settling velocity of finelydivided and collide particles under gravity also are so small that
ordinary sedimentation is not possible. It is necessary, therefore, to
use procedures which agglomerate the small particles into larger
aggregates, which have practical settling velocities. The term
"Coagulation" and "flocculation" have been used indiscriminately
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
69/97
to describe process of turbidity removal. "Coagulation" means to
bring together the suspended particles. The process describes the
effect produced by the addition of a chemical Al (SP) g to a
colloidal dispersion resulting in particle destabilization by a
reduction of force tending to keep particles apart. Rapid mixing isimportant at this stage to obtain. Uniform dispersion of the
chemical and to increase opportunity for particles to particle
contact. This operation is done by flash mixer in the
c1ariflocculator. Second stage of formation of settle able particles
from destabilized colloidal sized particles is termed a
"flocculation". Here coagulated particles grow in size by attaching
to each other. In contrast to coagulation where the primary force is
electrostatic or intrinsic, "flocculation" occurs by chemicalbridging. Flocculation is obtained by gentle and prolonged mixing
which converts the submicroscopic coagulated particle into
discrete, visible & suspended particles. At this stage particles are
large enough to settle rapidly under the influence of gravity
anomaly be removed.
If pretreatment of the water is not done efficiently then
consequences are as follows:
Si02 may escape with water which will increase the anionloading.
Organic matter may escape which may cause organic fouling
in the anion exchanger beds. In the 'pre-treatment plant
chlorine addition provision is normally made to combat
organic contamination.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
70/97
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
71/97
us see, what happens actually in each bed when water is passed
from one to another.
Resins, which are built on synthetic matrix
of a styrene divinely benzene copolymer, are manufactured in such
a way that these have the ability to, exchange one ion for another,hold it temporarily in chemical combination and give it to a strong
electrolytic solution. Suitable treatment is also given to them in
such a way that a particular resin absorbs only a particular group of
ions. Resins, when absorbing and releasing cationic portion of
dissolved salts, is called cation, exchanger resin and when
removing anionic portion is called anion exchanger resin. preset
trend is of employing 'strongly acidic cation exchanger resin and
strongly basic anion exchanger resin in a DM Plant of modernthermal power station. We may see that the chemically active
group in a cationic resin is SOx-H (normally represented by RH)
and in an anionic resin the active group is either tertiary amine or
quaternary ammonium group (normally the resin is represented by
ROH). The reaction of exchange may be further represented as
below
Cation Resin
RH + Na ------------------------- RNa + H2SO4
K K HCl
Mg Mg
Ca Ca HNO3
In the Resin in RemovedForm of in H2CO3 indegasser
Salts form tower
Anion Resin
ROH + H2SO4 ------------------ RSO4 + H2O
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
72/97
HCl Cl
HNO3 NO3
Mineral acid Resins in exhausted
Obtain from cation formexchanger
The water from the ex-cation contains
carbonic acid also sufficiently, which is very weak acid difficult to
be removed by strongly basic anion resin and causing hindrance to
remove silicate ions from the bed. It is therefore a usual practice to
remove carbonic acid before it is led to anion exchanger bed. The
ex-cation water is trickled in fine streams from top of a tall towerpacked with, rasching rings, and compressed air is passed from the
bottom. Carbonic acid breaks into C03 and water mechanically
(Henry's Law) with the carbon dioxide escaping into the
atmosphere. The water is accumulated in suitable storage tank
below the tower, called degassed water dump from where the same
is led to anion exchanger bed, using acid resistant pump.
The ex-anion water is fed to the mixed bedexchanger containing both cationic resin and anionic resin. This
bed not only takes care of sodium slip from cation but also silica
slip from anion exchanger very effectively. The final output from
the mixed bed is Exira-ordinarily pure water having less than
0.2/Mho conductivity 7.0 and silica content less than 0.02 pm. Any
deviation from the above quality means that the resins in mixed
bed are exhausted and need regeneration, regeneration of the
mixed bed first calls for suitable, back washing and settling, so that
the two types of resins are seperated from each other. Lighter anion
resin rises to the top and the heavier cation resin settles to the
bottom. Both the resins are then regenerated separately with alkali
and acid, rinsed to the desired value and air mixed, to mix the resin
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
73/97
again thoroughly. It is then put to final rinsing till the desired
quality is obtained.
It may be mentioned here that there are two types of
strongly basic anion exchanger. Type II resins are slightly less
basic than type I, but have higher regeneration efficiency than typeI. Again as type II resins are unable to remove silica effectively,
type I resins also have to be used for the purpose. As such, the
general condition so far prevailing in India, is to employ type II
resin in anion exchangers bed and type I resin in mixed bed (for
the anionic portion).
It is also a general convention to regenerate the
above two resins under through fare system i.e. the caustic soda
entering into mixed bed for regeneration, of type I anion resin, isutilized to regenerate type II resin in anion exchanger bed. The
content of utilizing the above resin and mode of regeneration is
now days being switched over from the economy to a higher cost
so as to have more stringent quality control of the final D.M.
Water.Internal Treatment
This final D.M effluent is then either led to
hot well of the condenser directly as make up to boilers, or being
stored in D.M. Water storage tanks first and then pumped for make
up purpose to boiler feed.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
74/97
As the D.M. Water has a good affinity to
absorb carbon dioxide and oxygen, and both are extremely harmful
to metal surfaces for their destruction like corrosion, these have to
be removed before it is fed to boiler. This is being done indesecrator. Still the residual oxygen which is remaining in the
water is neutralized by a suitable doze of hydrazine, at the point
after desecrator. To have further minimum corrosion, the pH of
feed water is to be maintained at around 9.0 for which purpose
ammonia in suitable doze is added to this make up water at a point
along with hydrazine as stated above.
**********************
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
75/97
STEAM TURBINE THEORY
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
76/97
Operating Principles
A steam turbine's two main parts are the cylinder andthe rotor.As the steam passes through the fixed blades or nozzles it
expands and its velocity increases. The high-velocity jet of steam
strikes the first set of moving blades. The kinetic energy of the
steam changes into mechanical energy, causing the shaft to rotate.
The steam then enters the next set of fixed blades and strikes the
next row of moving blades.
As the steam flows through the turbine, its pressure and
temperature decreases, while its volume increases. The decrease inpressure and temperature occurs as the steam transmits .energy to
the shaft and performs work. After passing through the last turbine
stage, the steam exhausts into the condenser or process steam
system.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
77/97
The kinetic energy of the steam changes into
mechanical erringly through the impact (impulse) or reaction of the
steam against the blades.
STEAM CYCLEThe thermal (steam) power plant uses a dual (vapour +
liquid) phase cycle. It is a closed cycle to enable the working fluid
(water) to be used again and again. The cycle used is "Rankine
Cycle" modified to include super heating of steam, regenerative
feed water heating and reheating of steam.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
78/97
On large turbines, it becomes economic to increase the
cycle efficiency by using reheat, which is a way of partially
overcoming temperature limitations. By returning partially
expanded steam to a reheat, the average temperature at which heat
is added is increased and by expanding this reheated steam to theremaining stages of the turbine, the exhaust wetness is
considerably less than it would otherwise be conversely, if the
maximum tolerable wetness is allowed, the initial pressure of the
steam can be appreciably increased.
TURBINE CLASSIFICATION
Impulse Turbine:In Impulse Turbine steam expands in fixed nozzles.
The high velocity steam from nozzles does work on moving blades
which causes the shaft to rotate. The essential features of impulse
turbine are that all pressure drops occur at nozzles and not on
blades.
A simple impulse turbine is not very efficient because it does
not fully use the velocity of the steam. Many impulse turbines are
velocity compounded. This means they have two or more sets ofmoving blades in each stage.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
79/97
Reaction Turbine:
In this type of turbine pressure is reduced at both fixed
& moving blades. Both fixed& moving blades act as nozzles.
Work done by the impulse effect of steam due to reversals ofdirection of high velocity steam. The expansion of steam takes
place on moving blades.
A reaction turbine uses the "kickback" force of the
steam as it leaves the moving blades and fixed blades have the
same shape and act like nozzles. Thus, steam expands, loses
pressure and increases in velocity as it passes through both sets of
blades. All reaction turbines are pressure-compounded turbines.
Compounding:
Several problems occur if energy of steam is converted
in single step & so compounding is done. Following are the typesof compounded turbine:
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
80/97
Velocity Compounded Turbine
Like simple turbine it has only one set of nozzle &
entire steam pressure drop takes place there. The kinetic energy of
steam fully on the nozzles is utilized in moving blades. The role of
fixed blades is to change the direction of steam jet & to guide it.
Pressure Compounded Turbine
This is basically a no. of single impulse turbines in
series or on the same shaft.
The exhaust of first turbine enters the nozzle of the next turbine.
Total pressure drop of steam does not take on first nozzle ring but
divided equally on all of them.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
81/97
Pressure Velocity Compounded Turbine
It is just the combination of the two compounding has
the advantages of allowing bigger pressure drops in each stage &
so fewer stages are necessary. Here for given pressure drop the
turbine will be shorter length but diameter will be increased.
Steam turbines may be classified into different categories
depending on their construction, the process by which heat dropis achieved, the initial and final conditions of steam used and
their industrial usage.
According to the direction of steam flow
Axial turbines
Radial turbines
According to the number of cylinder
Single - cylinder turbines.
Double- cylinder turbines.
Three-Cylinder turbines.
Four-Cylinder turbines.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
82/97
Multi - Cylinder turbines
According to the steam conditions at inlet toturbines
Low-pressure turbines Medium -pressure turbines
High-pressure
Turbines of very high pressures
Turbines of supercritical pressures
According to their usage in industry
Turbines with constant speed of rotation primarily used for
driving alternators. Steam turbines with variable speed meant for driving turbo
blowers, air circulators, pumps etc.
Turbines with variable speed: Turbines of this type are usually
employed in steamers, ships and railway locomotives (turbo
locomotives)
Main Turbine
The 210MW turbine is a tandem compounded type
machine comprising of H.P. & I.P. cylinders. The H.P. turbine
comprises of 12 stages the I.P. turbine has 11 stages & the L.P. has
four stages of double flow. The H.P. & I.P. turbine rotor are rigidly
compounded & the I.P. & the I.P. rotor by lens type semi flexible
coupling. All the three rotors are aligned on five bearings of which
the bearing no.2 is combined with thrust bearing.
The main superheated steam branches off into twostreams from the boiler and passes through the emergency stop
valve and control valve before entering, the governing wheel
chamber of the H.P. turbine. After expanding in the 12 stages in
the H.P. turbine the steam returned in the boiler for reheating.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
83/97
The reheated steam from the boiler enter I.P. turbine via
interceptor valves and control valves and after expanding enters
the L.P. turbine stage via 2 numbers of cross over pipes.
In the L.P. stage the steam expands in axially opposite
direction to counteract the trust and enters the condenser placed
directly below the L.P. turbine. The cooling water flowing
throughout the condenser tubes condenses the steam and the
condensate collected in the hot well of the condenser.
The condensate collected is pumped by means of
3*50% duty condensate pumps through L.P. heaters to deaerator
from where the boiler feed pump delivers the water to boiler
through H.P. heaters thus forming a closed cycle.
TURBINE CYCLEFresh steam from boiler is supplied to the turbine
through the emergency stop valve. From the stop valves steam is
supplied to control valves situated on H.P. cylinders on the front
bearing end. After expansion through 12 stages at the H.P. cylinder
steam flows back to boiler for reheating and reheated steam from
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
84/97
the boiler cover to the intermediate pressure turbine trough two
interceptor valves and four control valves mounted on the I.P.
turbine.
After flowing trough I.P. turbine steam enters the middlepart of the L.P. turbine through cross over pipes. In L.P. turbine the
exhaust steam condenses in the surface condensers welded directly
to the exhaust part of L.P. turbine.
The selection of extraction points and cold reheat pressure
has been done with a view to achieve the highest efficiency. These
are two extractions from H.P. turbine, four from I.P. turbine and
one from L.P. turbine. Steam at 1.10 to 1.03 g/sq cm Abs is
supplied for the gland sealing. Steam for this purpose is obtained
from deaerator through a collection where pressure of steam is
regulated.
From the condenser condensate is pumped with the help
of 3*50% capacity condensate pumps to deaerator through the low
pressure regenerative equipments.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
85/97
Feed water is pumped from deaerator to the boiler
through the H.P. heaters by means of 3*50% capacity feed pumps
connected before the H.P. heaters.
DESCRIPTION OF MAIN TURBINEMain Components of Turbine:
Emergency Stop Valve
Steam from the boiler is supplied to the turbine through
two emergency stop valves. The emergency stop valve operated by
hydraulic servomotor shuts off steam supply to the turbine whenthe turbo set is tripped. The emergency stop valves connected to
the four control valves through four flexible loop pipes of
Chromium-Molybdenum-Vanadium steel.
H.P. Cylinder
It is made of creep resisting Cr-Mo-V steel casting
made of two halves joined at the horizontal plane.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
86/97
The horizontal joint is secured with the help of studs
and nuts made of high creep resisting Cr-Mo-V steel forgings. To
ensure H.P. tightness the studs are tightened by heat to a
predetermined temperature with the help of electric heater.
H.P. Rotor
The H.P. rotor has discs integrally forged with the shafts
and is mechanical forming single Cr-Mo-V steel forging. A special
process to prevent abnormal rotor deflection thermally stabilizes
the rotor forging.
L.P. Rotor
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
87/97
It consists of shrunk fit discs on a shaft. The shaft is a
forging of Cr-Mo-V steel while the discs are of high strength Ni
steel forging.
The H.P. rotor is connected by rigid couplings whole the
I.P. rotor and L.P. rotor are connected by semi-flexible lens typecoupling. The rotors are dynamically balanced to a very precise
degree.
Turbine Bearings
The three turbine rotors are supported on fine bearings.
The second bearing from pedestal side is a combined radial thrust
bearing while all others are journal bearings.
Thrust Bearings
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
88/97
It is Mitchell type with bearing surface distributed over
a number of bearing surfaces. They are pivoted in housing on the
side of I.P. rotor thrust collar.
During operation on oil film is forced between pads
and thrust collar and there is a no metal-to-metal contact. A second
ring of pads on opposite side of thrust collar takes the axial thrust
as may occur under abnormal conditions.
L.P. Heaters
Turbine is provided with non-controlled extractions which
are utilized for heating the condensate from turbine bleeding
system. There are four L.P. heaters. They are equipped with
necessary safety valves in steam space level indicator for visual
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
89/97
level indication of heated steam. Condensate pressure vaccum
gauges are present for measurement of steam pressure.
Gland Steam Cooler
Gland steam cooler has been provided to suck and cool
the air steam mixture from the gland seats. It employs a small
ejector for which the working medium is steam of low parameters,
which can be taken either from the deaerator or auxiliary source.
The pressure and temperature of this steam should of this steam is
retrieved to the fullest possible extent as the gland steam cooler is
also interposed in the condensate heating cycle thereby improving
overall efficiency of the cycle.
TURBINE AUXILLARIECondensate Pumps
The function of these pumps is to pumps out thecondensate to the desecrator through ejectors, gland steam cooler,
and L.P. heaters. These pumps have four stages and since the
suction is at a negative pressure, special arrangements have been
made for providing sealing. This pump is rated generally for
160m3 hr. at a pressure 13.2 Kg/cm2.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
90/97
L.P. Heaters
Turbine has been provided with non-controlled
extractions which are utilized for heating the condensate, fromturbine bleed steam. There are 410w pressure heaters in which the
last four extractions are used. L.P. Heater-1 has two parts LPH-1A
and LPH-1B located in the upper parts of condenser A and
condenser B respectively. These are of horizontal type with shell
and tube construction. L.P.H. 2, 3 and 4 are of similar construction
and they are mounted in a row at 5M level. They are of vertical
construction with brass tubes the ends of which are expanded into
tube plate. The condensate flows in the "U" tubes in four passesand extraction steam washes the outside of the tubes. Condensate
passes thru' these four L.P. heaters in succession. These heaters
are equipped with necessary safety valves in the steam space level
indicator for visual level indication of heating steam condensate
pressure vacuum gauges for measurement of steam pressure etc
Feed Water System
The main equipments coming under this system are
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
91/97
Boiler Feed Pump: Three per unit of 50% capaCity each
located in the '0' meter level in the TG bay.
High Pressure Heaters: Normally three in number and are
situated in the TG bay.
Drip Pumps: Generally two in number of 100% capacity eachsituated beneath the LP heaters.
Turbine Lubricating Oil System: This consists of Main Oil
Pump (MOP) Starting Oil Pump (SOP), AC standby oil pumps
and emergency DC' oil pump and Jacking Oil Pump (JOP) (one
each per unit).Boiler Feed Pumps
This pump is horizontal and of barrel design driven byan Electric motor through a hydraulic coupling. All the bearings of
pump and motor are forced lubricated by a suitable oil lubricating
system with adequate protection to trip the pump if the lubrication
oil pressure falls below a preset value.
The high-pressure boiler feed pump is very expensive
machine which calls for a very careful operation and skilled
maintenance. The safety in operation and efficiency of the feed
pump depends largely on the reliable operation and maintenance.
Operating staff must be able to find out the causes of defect at the
very beginning which can be easily removed without endangering
the operator of the power plant and also without the expensive
dismantling of the high pressure feed pump.
The feed pump consists of pump barrel, into which is
mounted the inside stator together with rotor. The hydraulic part is
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
92/97
enclosed by the high pressure cover along with the balancing
device. The suction side of the barrel and the space in the high
pressure cover behind the balancing device are enclosed by the low
pressure covers along with the stuffing box casings. The brackets
of the radial bearing of the suction side and radial and thrustbearing of the discharge side are fixed to the low pressure covers.
The entire pumps are mounted on a foundation frame. The
hydraulic coupling and two claws coupling with coupling guards
are also delivered along with the pump. Water cooling and oil
lubricating are provided with their accessories.
Turbine Driven Boiler Feed Pump
The single cylinder turbine is of the axial flow type.
The live steam flows through the emergency stop valve and then
through the main Control Valves 5 nos. (Nozzle governing). These
valves regulate the steam supply through the turbine in accordance
with load requirements. The control valves are actuated by a lift
bar which is raised or lowered via a lever system by the relay
cylinder mounted on the turbine casing.
The journal bearings supporting the turbine shaft arearranged in the two bearing blocks. The front end -bearing block
also houses the thrust bearing, which locates the turbine shaft and
takes up "the axial forces.
There are 14 stages of reaction balding. The balancing
piston is provided at the. Steam admission side to compensate the
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
93/97
axial thrust to the maximum extent. Since the axial thrust varies
with the load, the residual thrust is taken up by the thrust bearing.
The leak off from the balancing piston is connected back to the
turbine after 9th stage.The turbine is provided with hydraulic and
electro-hydraulic governing system. A primary oil pump is used asa speed sensor for hydraulic governing and shall Probes are used as
a speed sensor for electro hydraulic governing.
Whenever steam is drawn from the cold reheat line or
auxiliary supply, steam flow is controlled by auxiliary control
valve. During this period the main control valves (4 nos.) will
remain fully opened and the bypass valve across it will remain
closed. (Bypass remains closed for a short period when change,
over from IP steam to CRH takes place).The steam exhaust for the BFP- Turbine is connected to
the main condenser and the turbine glands are sealed by gland
steam.
High Pressure Heaters
These are regenerative feed water heaters operating at
high pressure and located by the side of turbine. These are
generally vertical type and turbine bleed steam pipes are connected
to them.
HP heaters are connected in series on feed waterside
and by such arrangement, the feed water, after feed pump enters
the HP heaters. The steam is supplied to these heaters form the
bleed point of the turbine through motor operated valves. These
heaters have a group bypass protection on the feed waterside.
In the event f tube rupture in any of the HPH and the level of the
condensate rising to dangerous level, the group protection devicediverts automatically the feed water directly to boiler, thus
bypassing all the 3 H.P. heaters.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
94/97
Following fittings are generally provided on the HP heaters
Gauge glass for indicating the drain level.
Pressure gauge with three way cock.
Air Vent cock.
Safety valve shell side.
Seal pot.
Isolating valves.
High level alarm switch.
Speed Governor
It is directly coupled to the turbine rotor through
coupling and has been designed to maintain automatically the
speed of the turbo set. It is located with the front pedestals.
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
95/97
Load Limiter
Turbine is equipped with the load limiter used in special
cases to limit the opening of valves by speed governor.
Purpose: To limit the load rising beyond the set point, can bevaried over the entire load range.
Turbine Oil Lubricating System
This consists of main oil pump, starting oil pump emergency
D.C. oil pump and each per unit.
TYPES OF VALVES USED AND MAINTAINED IN TMD
Gate Valve
Regulating Valve
Non-Return Valve
Safety Valve
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
96/97
Valves are made of cast iron, cast steel, carbon steel,alloy steel.
Cast iron valves: 0-150 deg Cel temperature (used for water
lines).
Carbon steel valves: 150-425 deg Cel temperature (used for
water/steam lines).
Alloy steel valves: 425-535 deg Cel temperature (used for
steam lines).
*************************
Thanks
7/31/2019 Summer Training Project Report of Ntpc on Mech Engg
97/97