kstps
TRANSCRIPT
A
Practical Training
Taken
At
“Kota Super Thermal Power Station”
1
Submitted to the
Rajasthan Technical University, Kota
Training held from (1st June – 30th June, 2012)
Submitted To: - Submitted By:-
Mr. Mahesh Sharma Gaurav Panjwani
Head of Department B.Tech. (3rd year)
Roll no. 09/EPK/ME/015
MAHARISHI ARVIND COLLEGE OF ENGGINERING AND
TECHNOLOGY
KOTA, (RAJ) INDIA
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PREFACE
The rise in civilization is closely related to improvements in transportation and
requirement of energy that is not readily available in large quantities but is also readily
transportable. A very peculiar fact about electrical energy is that neither it is directly available in
nature nor it is directly used finally in this form, yet it is so widely produced and is the most
popular high grade energy.
The purpose behind training is to understand the difficult concepts in a better way
with gain of knowledge. Report starts with a brief introduction of KSTPS followed by
Generator, Turbine, switch gear, switch yard etc.
While writing the report and while I was on my training I was wondering
that science is as ever expanding field and the engineers working hard day and night and
make the life a gift for us.
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Acknowledgement
I express my sincere thanks to my project guide Mr. Sunil Madan Designation, Course
Coordinator, for guiding me right form the inception till the successful completion of the
summer training. I sincerely acknowledge him for extending their valuable guidance,
support for literature, critical reviews of project and the report and above all the moral
support he had provided to me with all stages of this report.
I would also like to thank the other supporting staff, for their help and cooperation
throughout my summer training.
I use this opportunity to express gratitude and debtness to Er. Mahesh Sharma Sir , HOD,
MECHANICAL DEPARTEMENT, MACET, Kota.
Gaurav Panjwani
(Name of the Student)
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Abstract
Kota is a rambling city that rests on the banks of the Chambal River and proudly testifies
the triumphs of the gallant Rajputs. The city's architectural wonders, manifested by the
majestic palaces and crenelated forts are a stunning sight to behold.
The large industrial powerhouses like the Kota Super Thermal Power Plant stand tall
in the city and beautifully complement the grandiose heritage edifices. In order to bring
about changes that would escalate the prospects of growth and development in the power
sector and to enforce the Power Sector Reforms, the Government of Rajasthan set up the
Rajasthan Rajya Vidyut Utpadan Nigam Ltd. (RVUN) in accordance with the
promulgations of the Companies Act-1956. Established on 19th July, 2000 the committee
is a torchbearer of Rajashthan's power sector. Under its aegis, the Kota Super Thermal
Power Station has total installed capacity of 1045 Megawatts. The Kota Super Thermal
Power Station has added another feather to its already brimming cap after receiving the
Union Ministry's Golden Shield award for four consecutive years spanning from 2000-
2004.
Kota Super Thermal Power Station has reached such dizzying heights of success that its
sixth unit was set up on 30th July, 2003. In this unit, maximum capacity on coal firing
was attained in less than 10 hours and the phenomenal completion of the project in less
than two years is a groundbreaking achievement for the nation. Besides the philanthropic
organization also has a social conscience. The organization plants nearly 3.5 lakhs
saplings every year, digs up dykes and water bodies and monitors the effusion of effluent
materials and ambient air quality in order to check the pollution level.
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Index of Contents
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Serial No. Particulars Page No.
1. Indian Power Industry
2. Profile of thermal industry in
Rajasthan.
3. Introduction to Kota Super Thermal
Power Station.
5. History of thermal power plants.
6. General definition of thermal power
plant.
7. Operations in a thermal power station.
8. Main parts of thermal power station.
9. Other systems
10 Fly ash utilization
11. SWOT Analysis
12. Conclusion
13. References
List of Figures
FIG. NO. DESCRIPTION PAGE NO.
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Fig.1 Different views of KTPS
Fig.2 View of KTPS from Chambal river
Fig.3 Block Diagram of Thermal Power Station
Fig.4 Operations In Thermal Power Station
Fig.5 Main Parts Of Thermal Power station
Fig.6 Cooling towers
Fig.7 Crossflow and Counterflow cooling
towers design
Fig.8 Transmission lines
Fig.9 Diagram of an electrical system.
Fig.10 Modern Steam Turbine Generator.
Fig.11 A rotor of a modern steam turbine, used in a power plant
Fig.12 Diagram of a typical water-cooled surface condenser
Fig.13 A simple control valve
Fig.14 Different types of deaerator
Fig.15 A Rankine cycle with a two-stage steam turbine and a single feedwater heater.
Fig.16 marine-type water tube boiler-see the steam drum at the top and feed drum
Fig.17 General view of superheater
Fig.18 Components of a centrifugal fan
Fig.19 Different Types Of Reheaters
Fig.20 The flames resulting from combustion
Fig.21 Economiser at KTPS
Fig.22 Schematic diagram of air preheater (APH) location.
Fig.23 Flue gas stack at KTPS ,kota
List of Tables
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Table No. Description Page No.
Table 1 Present Installed capacity of Rajasthan
Rajya Vidyut Utpadan Nigam
Table 2 Kota Thermal Power Station installed
capacity
Table 3 Awards received by KTPS
List of Abbreviations
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1). KSTPS - Kota Super Thermal Power Station.
2). NTPC - National Thermal Power Corporation.
3). RVUN - Rajasthan Vidhut Utpadan Nigam.
4). Ltd. - Limited
5). (BUs) - Billion Units
6). (SEBs) - State Electricity Boards
7).TPS - Thermal power station
8).EMF - Electro-motive force
9). HRSG - High recovery steam generator
10). FBA - Furnace Bottom Ash
11). IBA - Incinerator bottom ash
12). ESP - Electrostatic precipitator
13). APH - Air preheater
14). TBCCW - Turbine Building Closed Cooling Water
15). RPD - Rotating-plate design
16). DFT - Deareating feed tank
17). AC - Alternating current
18). RAPH - Regenerative air preheaters
19). HRSGs - Heat Recovery Steam Generators
20). SWOT - strength, weakness, opportunity, threat
Indian Power Industry
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Growth of Power Sector infrastructure in India since its Independence has been
noteworthy making India the third largest producer of electricity in Asia. Generating
capacity has grown manifold from 1,362 MW in 1947 to 141GW (as on 30.09.2004)...
India’s Total installed capacity of power sector has been 141 GW. This India’s 141GW
of total power is generated by its three different sectors, i.e., state sector, central sector
and private sector.
India has fifth largest generation capacity in the world. India’s transmission and
distribution network is of 6.6 million circuit km. This is considered to be third largest in
the world. As per above chart, thermal fuels like Coal, gas, oil constitute 64.6% of India’s
total installed capacity, followed by 24.7% from hydro power, 2.9% nuclear energy and
7.7% from other energy sources.
Industry Structure
Power sector structure in India has been very simple yet well defined. Majority of
Generation, Transmission and Distribution capacities are with either public sector
companies or with State Electricity Boards (SEBs). National thermal power corporation,
Nuclear Power Corporation, National Hydro Electric Power Corporation are the public
sector companies in India which are into power generation. TATA power, Reliance
Energy is domestic private players; Marubeni Corporation is international private
players in power sector. public sector is only power generation. Private sector
participation is increasing especially in Generation, transmission and Distribution.
Distribution licences for several cities are already with the private sector. Three large
ultra-mega power projects of 4000MW each have been recently awarded to the private
sector on the basis of global tenders.
Profile of Thermal Industry in Rajasthan
Present Installed capacity of Rajasthan Rajya Vidyut Utpadan Nigam is
3847.35 MW
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Power Station Capacity as on 31.03.09 Present Capacity
Suratgarh TPS 1500 MW 1500 MW
Kota STPS 1045 MW 1045 + 195 MW
Chhabra Super Thermal Power Station - 250 MW
Ramgarh Gas Power Plant 113.50MW 113.50MW
Mahi Hydel 140 MW 140 MW
MMH Schemes 23.85 MW 23.85 MW
Giral Lignite TPS 250 MW 250 MW
Dholpur CCPP 330 MW 330 MW
Total 3402.35 MW 3847 .35 MW
Rana Pratap Sagar Hydel PS (4X43 MW) 172 MW
Jawahar Sagar Hydel PS (3X33 MW) 99 MW
Total 271 MW
(Table 1)
Introduction to Kota Super Thermal Power Station
`
Kota Thermal Power Station is Rajasthan's First major coal power station. Presently it is in
operation with installed capacity of 1045MW.And one more unit of 250MW is slated for
commissioning in March 2009.
Stage Unit No. Capacity(MW) Synchronising Cost(Rs. Crore)
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Date
I 1 110 17.1.1983 143
2 110 13.7.1983
II 3 210 25.9.1988 480
4 210 1.5.1989
III 5 210 26.3.1994 480
IV 6 195MW 31.7.2003 635
V 7 195MW 30.5 2009 880
(Table 2)
Excellent Performance
Kota Thermal Power Station of RVUN is reckoned one of the best, efficient and prestigious
power stations of the country. KSTPS has established a record of excellence and has earned
meritorious productivity awards from the Ministry of Power, Govt.of India during 1984, 1987,
1989, 1991& every year since 1992-93 onwards.
Planned maintenance period reduced to 7% Approx.
Expected Power generation during 2007-08 around 90%·
Man Power is only 1.4 per MW·
Ash Utilisation 80% (Dry fly ash 100%)
Environmental Profile
Adequate measures have been taken to control pollution and ensure atmospheric emission
within the prescribed limits of Environment (Protection) Act1986.
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180 meter high stack have been provided to release flue gases into the atmosphere at an
approx. velocity 25m/sec. so as to disperse the emitted particulate matter over a wide spread
area. Adequate water spraying arrangements have been provided at coal unloading, transfer
and conveying system to arrest and restrict Fugitive Emission.
Regular monitoring of Stack Emission,Ambient Air Quality and Trade Effluent is carried out
Year Million Units Generated
Plant Load factor (%)
Award
1999-00 6314 84.44 Cash award of Rs.8.31.Lacs for productivity and Rs.6.19.Lacs each for saving in specific oil consumption for the years 1999 and 2000, Shields and Bronze medal.
2000-01 6437 86.60
Golden Shield award from Union Ministry of power
2001-02 6351 85.302002-03 6553 88.012003-04 6424 86.04
(Table 3)
(fig1). Different views of KSTPS
History of Thermal Power Plants.
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Reciprocating steam engines have been used for mechanical power sources since the 18th
Century, with notable improvements being made by James Watt. The very first
commercial central electrical generating stations in New York and London, in 1882, also
used reciprocating steam engines. As generator sizes increased, eventually turbines took
over due to higher efficiency and lower cost of construction. By the 1920s any central
station larger than a few thousand kilowatts would use a turbine prime mover.
(Fig.2) View of KTPS from Chambal River
Definition of Thermal Power Station
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A thermal power station is a power plant in which the prime mover is steam driven.
Water is heated, turns into steam and spins a steam turbine which either drives
an electrical generator or does some other work, like ship propulsion. After it passes
through the turbine, the steam is condensed in a condenser and recycled to where it was
heated; this is known as a Rankine cycle. The greatest variation in the design of thermal
power stations is due to the different fuel sources. Some prefer to use the term energy
center because such facilities convert forms of heat energy into electrical energy.
(Fig.3) Block Diagram of Thermal Power Station
Operations in Thermal Power Station
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Step wise operations in a thermal power plant are as follows:-
1).Coal is used as a fuel to boil the water.
2).Water is boiled to form pressurized steam.
3).Pressurised steam is the force that causes the turbine to rotate at a very high speed.
4).Low pressure steam after pushing through the turbine, it’s going into the condenser.
5).Condenser – the place where the steam is condensed back ti its liquid form .Then the
process is repeated.
(Fig 4.) Operations in Thermal Power Station
Main Parts of Thermal Power station
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1. Cooling tower 9. Steam Control valve17. Forced,induced
draught (draft) fan
2. Cooling water pump 10. Deaerator 18. Reheater
3. Transmission line (3-phase) 11. Feedwater heater19. Combustion air
intake
4. Step-up transformer (3-phase) 12. Coal hopper 20. Economiser
5. Electrical generator (3-phase) 13. Coal pulverizer 21. Air preheater
6. Low,intermediate,high pressure steam
turbine
14. Boiler & steam
drum22. Precipitator
7. Condensate pump 15. Bottom ash hopper 23. Flue gas stack
8. Surface condenser 16. superheater
(Fig. 5) Main Parts of Thermal Power station
1). Cooling Tower
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Cooling towers are heat removal devices used to transfer process waste heat to
the atmosphere. Cooling towers may either use the evaporation of water to remove
process heat and cool the working fluid to near the wet-bulb air temperature or rely solely
on air to cool the working fluid to near the dry-bulb air temperature. Common
applications include cooling the circulating water used in oil refineries, chemical
plants, power stations and building cooling. The towers vary in size from small roof-top
units to very large hyperboloid structures (as in Image 1) that can be up to 200 metres tall
and 100 metres in diameter, or rectangular structures (as in Image 2) that can be over 40
metres tall and 80 metres long. Smaller towers are normally factory-built, while larger
ones are constructed on site.
(Fig. 6) cooling towers
Classification of cooling towers
- Crossflow
Crossflow is a design in which the air flow is directed perpendicular to the water flow
(see diagram below). Air flow enters one or more vertical faces of the cooling tower to
meet the fill material. Water flows (perpendicular to the air) through the fill by gravity.
The air continues through the fill and thus past the water flow into an open plenum area.
A distribution or hot water basin consisting of a deep pan with holes or nozzles in the
bottom is utilized in a crossflow tower. Gravity distributes the water through the nozzles
uniformly across the fill material.
- Counterflow
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In a counterflow design the air flow is directly opposite of the water flow (see diagram
below). Air flow first enters an open area beneath the fill media and is then drawn up
vertically. The water is sprayed through pressurized nozzles and flows downward through
the fill, opposite to the air flow.
(Fig 7.) Crossflow and Counterflow cooling towers design
iii). Cooling tower as a flue gas stack
At some modern power stations, equipped with flue gas purification like Kota Super
Thermal Power Station the cooling tower is used as a flue gas stack (industrial chimney).
At plants without flue gas purification, this causes problems with corrosion.
2). Cooling Water Pump
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In power plants, water cooling systems are typically used for removing heat
(cooling). These water cooling systems are, in turn, then cooled by the ultimate
cooling system river, lake, sea, or ocean water
These cooling water systems have separate subsystems, each with: one or more
pumps for circulating fluid through the watercooling systems one heat exchanger
to transfer heat to the Ultimate water Cooling System an automatic valve to
regulate the heat removed from the Component Cooling system to the Ultimate
cooling system. There is usually a shared tank, called a surge tank, for the
redundant sub-systems is used as a makeup supply if there is not enough water in
the system, or to handle the surge (increase in level) if there is too much water in
the system. Turbine Building Closed Cooling Water Systems
The Turbine Building Closed Cooling Water (TBCCW) Systems cool heat exchangers
for:
1. Feedwater Pump Seal Water
2. Condensate Pump Seal Water
3. Heater Drain Pump Seal Wate
3). Electric Power Transmission
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Electric power transmission is the bulk transfer of electrical energy, a process in the
delivery of electricity to consumers. A power transmission network typically
Connects power plants to multiple substations near a populated area. The wiring from
substations to customers is referred to as electricity distribution, following the historic
business model separating the wholesale electricity transmission business
from distributors who deliver the electricity to the homes. [1] Electric power transmission
allows distant energy sources (such as hydroelectric power plants) to be connected to
consumers in population centers, and may allow exploitation of low-grade fuel resources
such as coal that would otherwise be too costly to transport to generating facilities.
(Fig 8) Transmission lines
Transmission lines;-
Usually transmission lines use three phase alternating current (AC). Single phase AC
current is sometimes used in a railway electrification system.High-voltage direct
current systems are used for long distance transmission, or some undersea cables, or for
connecting two different ac networks.
Electricity is transmitted at high voltages (110 kV or above) to reduce the energy lost in
transmission. Power is usually transmitted as alternating current through overhead power
lines. Underground power transmission is used only in densely populated areas because
of its higher cost of installation and maintenance when compared with overhead wires,
and the difficulty of voltage control on long cables.
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(Fig.9) Diagram of an electrical system.
i). Overhead transmission:-
Overhead conductors are not covered by insulation. The conductor material is nearly
always an aluminium alloy, made into several strands and possibly reinforced with steel
strands. Copper was sometimes used for overhead transmission but aluminium is lower in
weight for equivalent performance, and much lower in cost. Overhead conductors are a
commodity supplied by several companies worldwide. Improved conductor material and
shapes are regularly used to allow increased capacity and modernize transmission
circuits. Thicker wires would lead to a relatively small increase in capacity due to
the skin effect that causes most of the current to flow close to the surface of the wire.
ii). Underground transmission:-
Electric power can also be transmitted by underground power cables instead of overhead
power lines. They can assist the transmission of power across.Densely populated urban
Areas where land is unavailable or planning consent is difficult Rivers and other natural
obstacles Land with outstanding natural or environmental heritage Areas of significant or
prestigious infrastructural development Land whose value must be maintained for future
urban expansion and rural development
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4). Transformer
A transformer is a device that transfers electrical energy from one circuit to another
through inductively coupled conductors—the transformer's coils. A varying current in the
first or primary winding creates a varying magnetic flux in the transformer's core, and
thus a varying magnetic field through the secondary winding. This varying magnetic
field induces a varying electromotive force (EMF) or "voltage" in the secondary winding.
This effect is called mutual induction.
Transformers can be classified in different ways:
By power capacity: from a fraction of a volt-ampere (VA) to over a thousand
MVA;
By frequency range: power-, audio-, or radio frequency;
By voltage class: from a few volts to hundreds of kilovolts;
By cooling type: air cooled, oil filled, fan cooled, or water cooled;
By application: such as power supply, impedance matching, output voltage and
current stabilizer, or circuit isolation;
By end purpose: distribution, rectifier, arc furnace, amplifier output;
By winding turns ratio: step-up, step-down, isolating (equal or near-equal ratio),
variable.
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5). Electrical Generator
In electricity generation, an electrical generator is a device that converts mechanical
energy to electrical energy, generally using electromagnetic induction. The reverse
conversion of electrical energy into mechanical energy is done by a motor; motors and
generators have many similarities. A generator forces electric charges to move through an
external electrical circuit, but it does not create electricity or charge, which is already
present in the wire of its windings. It is somewhat analogous to a water pump, which
creates a flow of water but does not create the water inside. Thesource of mechanical
energy may be a reciprocating or turbine steam engine, water falling through a turbine or
waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed
air or any other source of mechanical energy.
(Fig.10) Steam Turbine Generator.
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6). Steam Turbine
A steam turbine is a mechanical device that extracts thermal energy from
pressurized steam, and converts it into rotary motion.
It has almost completely replaced the reciprocating piston steam engine(invented
by Thomas Newcomen and greatly improved by James Watt) primarily because of its
greater thermal efficiency and higher power-to-weight ratio. Because the turbine
generates rotary motion, it is particularly suited to be used to drive an electrical generator
- about 80% of all electricity generation in the world is by use of steam turbines. The
steam turbine is a form of heat engine that derives much of its improvement
inthermodynamic efficiency through the use of multiple stages in the expansion of the
steam, which results in a closer approach to the idealreversible process.
(Fig.11) A rotor of a modern steam turbine, used in a power plant
Types of turbines
a). Impulse turbines
An impulse turbine has fixed nozzles that orient the steam flow into high speed jets.
These jets contain significant kinetic energy, which the rotor blades, shaped like buckets,
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convert into shaft rotation as the steam jet changes direction. A pressure drop occurs
across only the stationary blades, with a net increase in steam velocity across the stage.
As the steam flows through the nozzle its pressure falls from inlet pressure to the exit
pressure (atmospheric pressure, or more usually, the condenser vacuum). Due to this
higher ratio of expansion of steam in the nozzle the steam leaves the nozzle with a very
high velocity. The steam leaving the moving blades is a large portion of the maximum
velocity of the steam when leaving the nozzle. The loss of energy due to this higher exit
velocity is commonly called the "carry over velocity”.
b). Reaction turbines
In the reaction turbine, the rotor blades themselves are arranged to form convergent
nozzles. This type of turbine makes use of the reaction force produced as the steam
accelerates through the nozzles formed by the rotor. Steam is directed onto the rotor by
the fixed vanes of the stator. It leaves the stator as a jet that fills the entire circumference
of the rotor. The steam then changes direction and increases its speed relative to the speed
of the blades. A pressure drop occurs across both the stator and the rotor, with steam
accelerating through the stator and decelerating through the rotor, with no net change in
steam velocity across the stage but with a decrease in both pressure and temperature,
reflecting the work performed in the driving of the rotor.
Types
Steam turbines are made in a variety of sizes ranging from small 1 hp (0.75 kW) units
(rare) used as mechanical drives for pumps, compressors and other shaft driven
equipment, to 2,000,000 hp (1,500,000 kW) turbines used to generate electricity. There
are several classifications for modern steam turbines.
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7). Condensate Pump
A condensate pump is a specific type of pump used to pump the condensate (water)
produced in an HVAC (heating or cooling),refrigeration, condensing boiler furnace
or steam system. They may be used to pump the condensate produced from latent water
vapor in any of the following gas mixtures:
- conditioned (cooled or heated) building air
- refrigerated air in cooling and freezing systems
- Steam in heat exchangers and radiators
- the exhaust stream of very-high-efficiency furnaces
Construction and operation
Condensate pumps as used in hydro systems are usually electrically powered centrifugal
pumps. As used in homes and individual heat exchangers, they are often small and rated
at a fraction of a horsepower, but in commercial applications they range in size up to
many horsepower and the electric motor are usually separated from the pump body by
some form of mechanical coupling. Large industrial pumps may also serve as the
feedwater pump for returning the condensate under pressure to a boiler.
Condensate pumps usually run intermittently and have a tank in which condensate can
accumulate. Eventually, the accumulating liquid raises afloat switch energizing the pump.
The pump then runs until the level of liquid in the tank is substantially lowered. Some
pumps contain a two-stage switch. As liquid rises to the trigger point of the first stage, the
pump is activated. If the liquid continues to rise (perhaps because the pump has failed or
its discharge is blocked), the second stage will be triggered. This stage may switch off the
HVAC equipment (preventing the production of further condensate); trigger an alarm, or
both.
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8). Surface Condenser
i). Purpose
In thermal power plants, the primary purpose of a surface condenser is to condense the
exhaust steam from a steam turbine to obtain maximum efficiency and also to convert the
turbine exhaust steam into pure water (referred to as steam condensate) so that it may be
reused in the steam generator or boiler as boiler feed water.
ii). Diagram of water-cooled surface condenser
(Fig 12) Diagram of a typical water-cooled surface condenser
The surface condenser is a shell and tube heat exchanger in which cooling water is
circulated through the tubes. The exhaust steam from the low pressure turbine enters the
shell where it is cooled and converted to condensate (water) by flowing over the tubes.
Such condensers use steam ejectors or rotary motor-driven exhausters for continuous
removal of air and gases from the steam side to maintain vacuum. For best efficiency, the
temperature in the condenser must be kept as low as practical in order to achieve the
lowest possible pressure in the condensing steam. Since the condenser temperature can
almost always be kept significantly below 100 oC where the vapor pressure of water is
much less than atmospheric pressure, the condenser generally works under vacuum.
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9). Steam Control Valves
Control valves are valves used to control conditions such as flow, pressure, temperature,
and liquid level by fully or partially opening or closing in response to signals received
from controllers that compare a "set point" to a "process variable" whose value is
provided by sensors that monitor changes in such conditions. [1]
The opening or closing of control valves is done by means of electrical,
hydraulic or pneumatic systems. Petitioners are used to control the opening or closing of
the actuator based on Electric, or Pneumatic Signals. These control signals, traditionally
based on 3-15psi (0.2-1.0bar), more common now are 4-20mA signals for industry, 0-
10V for HVAC systems, & the introduction of "Smart" systems, HART, Field bus
Foundation, & Prefabs being the more common protocols.
(Fig 13) A simple control valve
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10). Deaerator
A Deaerator is a device that is widely used for the removal of air and other
dissolved gases from the feedwater to steam-generating boilers. In particular,
dissolved oxygen in boiler feed waters will cause serious corrosion damage in steam
systems by attaching to the walls of metal piping and other metallic equipment and
forming oxides (rust). It also combines with any dissolved carbon dioxide to
form carbonic acid that causes further corrosion. Most Deaerator is designed to remove
oxygen down to levels of 7 ppb by weight (0.0005 cm³/L) or less.
There are two basic types of deaerators, the tray-type and the spray-type:
The tray-type (also called the cascade-type) includes a vertical domed deaeration section
mounted on top of a horizontal cylindrical vessel which serves as the deaerated boiler
feedwater storage tank.
The spray-type consists only of a horizontal (or vertical) cylindrical vessel which serves
as both the deaeration section and the boiler feedwater storage tank.
a). Tray-type deaerator b). Spray-type deaerator
(Fig 14) Different types of deaerator
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11). Feedwater Heater
(Fig. 15) A Rankine cycle with a two-stage steam turbine and a single feedwater
heater.
A feedwater heater is a power plant component used to pre-heat water delivered to
a steam generating boiler. Preheating the feedwater reduces the irreversibility’s involved
in steam generation and therefore improves the thermodynamic efficiency of the
system. [4] This reduces plant operating costs and also helps to avoid thermal shock to the
boiler metal when the feedwater is introduced back into the steam cycle.
In a steam power plant (usually modeled as a modified Rankine cycle), feedwater heaters
allow the feedwater to be brought up to the saturation temperature very gradually. This
minimizes the inevitable irreversibility’s associated with heat transfer to the working
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fluid (water). See the article on the Second Law of Thermodynamics for a further
discussion of such irreversibility’s.
i). Cycle discussion and explanation
It should be noted that the energy used to heat the feedwater is usually derived from
steam extracted between the stages of the steam turbine. Therefore, the steam that would
be used to perform expansion work in the turbine (and therefore generate power) is not
utilized for that purpose. The percentage of the total cycle steam mass flow used for the
feedwater heater is termed the extraction fraction [4] and must be carefully optimized for
maximum power plant thermal efficiency since increasing this fraction causes a decrease
in turbine power output.
Feedwater heaters can also be open and closed heat exchangers. An open feedwater
heater is merely a direct-contact heat exchanger in which extracted steam is allowed to
mix with the feedwater. This kind of heater will normally require a feed pump at both the
feed inlet and outlet since the pressure in the heater is between the boiler pressure and
the condenser pressure. A deaerator is a special case of the open feedwater heater which
is specifically designed to remove non-condensable gases from the feedwater.
Closed feedwater heaters are typically exchangers where the feedwater passes throughout
the tubes and is heated by turbine extraction steam. These do not require separate pumps
before and after the heater to boost the feedwater to the pressure of the extracted steam as
with an open heater.
Feedwater heaters are used in both fossil- and nuclear-fueled power plants. Smaller
versions have also been installed on locomotives, portable and stationary engines.
An economiser serves a similar purpose to a feedwater heater, but is technically different.
Instead of using actual cycle steam for heating, it uses the lowest-temperature flue
gas from the furnace (and therefore does not apply to nuclear plants) to heat the water
before it enters the boiler proper. This allows for the heat transfer between the furnace
and the feedwater occurring across a smaller average temperature gradient (for the steam
generator as a whole). System efficiency is therefore further increased when viewed with
respect to actual energy content of the fuel.
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12). Coal Hopper
Coal is a readily combustible black or brownish-black sedimentary rock normally
occurring in rock strata in layers or veins called coal beds. The harder forms, such
as anthracite coal, can be regarded as metamorphic rock because of later exposure to
elevated temperature and pressure. It is composed primarily ofcarbon along with variable
quantities of other elements, chiefly sulfur, hydrogen, oxygen and nitrogen.
Peat, considered to be a precursor of coal, has industrial importance as a fuel in
some regions, for example, Ireland and Finland.
Lignite, also referred to as brown coal, is the lowest rank of coal and used almost
exclusively as fuel for electric power generation. Jet is a compact form of lignite
that is sometimes polished and has been used as an ornamental stone since
the Iron Age.
Sub-bituminous coal, whose properties range from those of lignite to those of
bituminous coal are used primarily as fuel for steam-electric power generation.
Additionally, it is an important source of light aromatic hydrocarbons for
the chemical synthesis industry.
Bituminous coal, dense mineral, black but sometimes dark brown, often with
well-defined bands of bright and dull material, used primarily as fuel in steam-
electric power generation, with substantial quantities also used for heat and power
applications in manufacturing and to make coke.
Anthracite, the highest rank; a harder, glossy, black coal used primarily for
residential and commercial space heating. It may be divided further into
metamorphically altered bituminous coal and petrified oil, as from the deposits in
Pennsylvania.
Graphite, technically the highest rank, but difficult to ignite and is not so
commonly used as fuel: it is mostly used in pencils and, when powdered, as
a lubricant
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Coal is primarily used as a solid fuel to produce electricity and heat through combustion.
World coal consumption was about 6,743,786,000 short tons in 2006 and is expected to
increase 48% to 9.98 billion short tons by 2030. China produced 2.38 billion tons in
2006. India produced about 447.3 million tons in 2006. 68.7% of China's electricity
comes from coal. The USA consumes about 14% of the world total, using 90% of it for
generation of electricity.
Fuel processing
Coal is prepared for use by crushing the rough coal to pieces less than 2 inches (5 cm) in
size. The coal is then transported from the storage yard to in-plant storage silos by
rubberized conveyor belts at rates up to 4,000 tons/hour.
In plants that burn pulverized coal, silos feed coal pulverizers (coal mills) that take the
larger 2-inch pieces, grind them to the consistency offace powder, sort them, and mix
them with primary combustion air which transports the coal to the furnace and preheats
the coal to drive off excess moisture content. A 500 MWe plant will have six such
pulverizers, five of which can supply coal to the furnace at 250 tons per hour under full
load.
In plants that do not burn pulverized coal, the larger 2-inch pieces may be directly fed
into the silos which then feed the cyclone burners, a specific kind of combustor that can
efficiently burn larger pieces of fuel.
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13). Coal Pulverizer
A 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.
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.
- Demolition pulverizer
An attachment fitted to an excavator. Commonly used in demolition work to break up
large pieces of concrete.
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14). Boiler and Boiler Steam Drum
A boiler is an enclosed vessel that provides a means for combustion heat to be
transferred into water until it becomes heated water or steam. The hot water or steam
under pressure is then usable for transferring the heat to a process. Water is a useful and
cheap medium for transferring heat to a process. When water is boiled into steam its
volume increases about 1,600 times, producing a force that is almost as explosive as
gunpowder. This causes the boiler to be extremely dangerous equipment that must be
treated with utmost care.
Boiler operation
The boiler is a rectangular furnace about 50 feet (15 m) on a side and 130 feet (40 m) tall.
Its walls are made of a web of high pressure steel tubes about 2.3 inches (60 mm) in
diameter.
Pulverized coal is air-blown into the furnace from fuel nozzles at the four corners and it
rapidly burns, forming a large fireball at the center. The thermal radiation of the fireball
heats the water that circulates through the boiler tubes near the boiler perimeter. The
water circulation rate in the boiler is three to four times the throughput and is typically
driven by pumps. As the water in the boiler circulates it absorbs heat and changes into
steam at 700 °F (370 °C) and 3,200 psi (22 MPa). It is separated from the water inside a
drum at the top of the furnace. The saturated steam is introduced into superheat pendant
tubes that hang in the hottest part of the combustion gases as they exit the furnace. Here
the steam is superheated to 1,000 °F (540 °C) to prepare it for the turbine.
Plants that use gas turbines to heat the water for conversion into steam use boilers known
as HRSGs, Heat Recovery Steam Generators. The exhaust heat from the gas turbines is
used to make superheated steam that is then used in a conventional water-steam
generation cycle, as described in Gas turbine combined-cycle plants section below
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The water supplied to the boiler that is converted into steam is called feed water.
There are virtually infinite numbers of boiler designs but generally they fit into
one of two categories:
1. Fire tube or "fire in tube" boilers; contain long steel tubes through which
the hot gasses from a furnace pass and around which the water to be
converted to steam circulates. Fire tube boilers, typically have a lower
initial cost, are more fuel efficient and easier to operate, but they are
limited generally to capacities of 25 tons/hr and pressures of 17.5
Kg/cm
2. Water tube or "water in tube" boilers in which the conditions are
reversed with the water passing through the tubes and the hot gasses
passing outside the tubes. These boilers can be of single- or multipledrum
type. These boilers can be built to any steam capacities and
pressures, and have higher efficiencies than fire tube boilers.
Steam drums are a regular feature of water tube boilers. It is a reservoir of water/steam
at the top end of the water tubes in the water-tube boiler. They store the steam generated
in the water tubes and act as a phase separator. The difference in densities between hot
and cold water helps in the accumulation of the "hotter"-water/and saturated-steam into
the steam-drum.
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(Fig 16) marine-type water tube boiler-see the steam drum at the top and feed drum
15). Bottom Ash Hopper
Bottom ash refers to the non-combustible constituents of coal with traces of
combustibles embedded in forming clinkers and sticking to hot side walls of a coal-
burning furnace during its operation. The portion of the ash that escapes up the chimney
or stack is, however, referred to as fly ash. The clinkers fall by themselves into the water
or sometimes by poking manually, and get cooled.
The clinker lumps get crushed to small sizes by clinker grinders mounted under water and
fall down into a trough from where a water ejector takes them out to a sump. From there
it is pumped out by suitable rotary pumps to dumping yard far away. In another
arrangement a continuous link chain scrapes out the clinkers from under water and feeds
them to clinker grinders outside the bottom ash hopper.
Bottom ash may be used as an aggregate in road construction and concrete, where it is
known as furnace bottom ash (FBA), to distinguish it from incinerator bottom ash (IBA),
the non-combustible elements remaining after incineration. It was also used in the
making of the concrete blocks used to construct many high-rise flats in London in the
1960s
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16). Superheater
A super heater is a device in a steam engine that heats the steam generated by
the boiler again, increasing its thermal energy and decreasing the likelihood
that it will condense inside the engine. Super heaters increase the efficiency of
the steam engine, and were widely adopted. Steam which has been
superheated is logically known as superheated steam; non-superheated steam
is called saturated steam or wet steam.
Super heaters were applied to steam locomotives in quantity from the early
20th century, to most steam vehicles, and to stationary steam engines
including power stations.
(Fig. 17) General view of superheater
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17). Centrifugal Fan
A centrifugal fan (also squirrel-cage fan, as it looks like a hamster wheel) is a
mechanical device for moving air or gases. It has a fan wheel composed of a number of
fan blades, or ribs, mounted around a hub. As shown in Figure 1, the hub turns on
a driveshaft that passes through the fan housing. The gas enters from the side of the
fan wheel, turns 90 degrees and accelerates due to centrifugal force as it flows over the
fan blades and exits the fan housing. [1]
(Fig 18): Components of a centrifugal fan
Centrifugal fans can generate pressure rises in the gas stream. Accordingly, they are well-
suited for industrial processes and air pollution control systems. They are also common in
central heating/cooling systems.
a) Fan components
The major components of a typical centrifugal fan include the fan wheel, fan housing,
drive mechanism, and inlet and/or outlet dampers.
b). Fan dampers
Fan dampers are used to control gas flow into and out of the centrifugal fan. They may be
installed on the inlet side or on the outlet side of the fan, or both. Dampers on the outlet
side impose a flow resistance that is used to control gas flow. Dampers on the inlet side
are designed to control gas flow and to change how the gas enters the fan wheel.Inlet
dampers reduce fan energy usage due to their ability to affect the airflow pattern into the
fan.
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18). Reheater
Power plant furnaces may have a reheater section containing tubes heated by hot flue
gases outside the tubes. Exhaust steam from the high pressure turbine is rerouted to go
inside the reheater tubes to pickup more energy to go drive intermediate or lower pressure
turbines.
(Fig 19). Different Types of Reheaters
19). Combustion
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Combustion or burning is a complex sequence of exothermic chemical reactions
between a fuel (usually hydrocarbon) and an oxidant accompanied by the production
of heat or both heat and light in the form of either a glow or flames, appearance of light
flickering.
(Fig. 20)The flames resulting from combustion
Direct combustion by atmospheric oxygen is a reaction mediated
by radical intermediates. The conditions for radical production are naturally produced
by thermal runaway, where the heat generated by combustion is necessary to maintain the
high temperature necessary for radical production.
In a complete combustion reaction, a compound reacts with an oxidizing element, such
as oxygen or fluorine, and the products are compounds of each element in the fuel with
the oxidizing element. For example:
CH4 + 2O2 → CO2 + 2H2O
CH2S + 6F2 → CF4 + 2HF + SF6
A simpler example can be seen in the combustion of hydrogen and oxygen, which is a
commonly used reaction in rocket engines:
2H2 + O2 → 2H2O (g) + heat
The result is water vapor.
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In the large majority of real-world uses of combustion, air is the source of oxygen (O2).
In air, each kg (lab) of oxygen is mixed with approximately 3.76 kg (lbm) of nitrogen.
The resultant flue gas from the combustion will contain nitrogen:
CH4 + 2O2 + 7.52N2 → CO2 + 2H2O + 7.52N2 + heat
When air is the source of the oxygen, nitrogen is by far the largest part of the resultant
flue gas.
In reality, combustion processes are never perfect or complete. In flue gases from
combustion of carbon (as in coal combustion) or carbon compounds (as in combustion
of hydrocarbons, wood etc.) both unburned carbon (as soot) and carbon compounds
(CO and others) will be present. Also, when air is the oxidant, some nitrogen can be
oxidized to various nitrogen oxides (NOx).
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20). Economizer
Economizers, or in British English economisers, are mechanical devices intended to
reduce energy consumption, or to perform another useful function like preheating a fluid.
The term economizer is used for other purposes as well. Boiler, powerplant, and heating,
ventilating, and air-conditioning (HVAC) uses are discussed in this article. In simple
terms, an economizer is a heat exchanger.
i). Powerplant
Economizers are commonly used as part of a heat recovery steam generator in
a combined cycle power plant. In an HRSG, water passes through an economizer, then
a boiler and then a superheater. The economizer also prevents flooding of the boiler with
liquid water that is too cold to be boiled given the flow rates and design of the boiler.
A common application of economizers in steam powerplant is to capture the waste heat
from boiler stack gases (flue gas) and transfer it to the boiler feedwater. This raises the
temperature of the boiler feedwater thus lowering the needed energy input, in turn
reducing the firing rates to accomplish the rated boiler output. Economizers lower stack
temperatures which may cause condensation of acidic combustion gases and serious
equipment corrosion damage if care is not taken in their design and material selection.
(Fig 21): Economizer at KSTPS
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21). Air Preheater
An air preheater (APH) is a general term to describe any device designed to
heat air before another process (for example, combustion in a boiler) with the primary
objective of increasing the thermal efficiency of the process. They may be used alone or
to replace a recuperative heat system or to replace a steam coil.
In particular, this article describes the combustion air preheaters used in
large boilers found in thermal power stations producing power from e.g. fossil
fuels, biomasses or waste.
(Fig. 22) Schematic diagram of air preheater (APH) location.
The purpose of the air preheater is to recover the heat from the boiler flue gas which
increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue
gas. As a consequence, the flue gases are also sent to the flue gas stack (or chimney) at a
lower temperature, allowing simplified design of the ducting and the flue gas stack. It
also allows control over the temperature of gases leaving the stack (to meet emissions
regulations, for example).
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22). Electrostatic Precipitator
An electrostatic precipitator (ESP), or electrostatic air cleaner is particulate collection
device that removes particles from a flowing gas (such as air) using the force of an
induced electrostatic charge. Electrostatic precipitators are highly
efficient filtration devices that minimally impede the flow of gases through the device,
and can easily remove fine particulate matter such as dust and smoke from the air
stream. [1] . In contrast to wet scrubbers which apply energy directly to the flowing fluid
medium, an ESP applies energy only to the particulate matter being collected and
therefore is very efficient in its consumption of energy (in the form of electricity).
i). Modern industrial electrostatic precipitators
ESOPs continue to be excellent devices for control of many industrial particulate
emissions, including smoke from electricity-generating utilities (coal and oil fired), salt
cake collection from black liquor boilers in pulp mills, and catalyst collection from
fluidized bed catalytic cracker units in oil refineries to name a few. These devices treat
gas volumes from several hundred thousand ACFM to 2.5 million ACFM (1,180 m³/s) in
the largest coal-fired boiler applications. For a coal-fired boiler the collection is usually
performed downstream of the air preheater at about 320 dig’s which provides optimal
resistively of the coal-ash particles..
The original parallel plate-weighted wire design (described above) has evolved as more
efficient (and robust) discharge electrode designs were developed, today focusing on
rigid (pipe-frame) discharge electrodes to which many sharpened spikes are attached
(barbed wire), maximizing corona production. Modern controls, such as an automatic
voltage control, minimize sparking and prevent arcing (sparks are quenched within 1/2
cycle of the TR set), avoiding damage to the components.
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23). Flue gas stack
A flue gas stack is a type of chimney, a vertical pipe, channel or similar structure
through which combustion product gases called flue gases are exhausted to the outside
air. Flue gases are produced when coal, oil,natural gas, wood or any other fuel
is combusted in an industrial furnace, apower plant's steam-generating boiler, or other
large combustion device. Flue gas is usually composed of carbon dioxide (CO2) and
water vapor as well as nitrogen and excess oxygen remaining from the intake combustion
air. It also contains a small percentage of pollutants such as particulate matter, carbon
monoxide, nitrogen oxides and sulfur oxides. The flue gas stacks are often quite tall, up
to 400 meters (1300 feet) or more, so as to disperse the exhaust pollutants over a greater
area and thereby reduce theconcentration of the pollutants to the levels required by
governmental environmental policy and environmental regulation.
(Fig. 23)
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When the flue gases are exhausted from stoves, ovens, fireplaces, or other small
sources within residential abodes, restaurants, hotels, or other public buildings
and small commercial enterprises, their flue gas stacks are referred to as
chimneys.
i).Stack design
Designing chimneys and stacks to provide the correct amount of natural draft involves a
great many factors such as:
1. The height and diameter of the stack.
2. The desired amount of excess combustion air needed to assure complete
combustion.
3. The temperature of the flue gases leaving the combustion zone.
4. The composition of the combustion flue gas, which determines the flue
gas density.
5. The frictional resistance to the flow of the flue gases through the chimney or
stack, which will vary with the materials used to construct the chimney or stack.
6. The heat loss from the flue gases as they flow through the chimney or stack.
7. The local atmospheric pressure of the ambient air, which is determined by the
local elevation above sea level.
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Other Systems
(1). Monitoring and alarm system
Most of the power plant operational controls are automatic. However, at times, manual
intervention may be required. Thus, the plant is provided with monitors and alarm
systems that alert the plant operators when certain operating parameters are seriously
deviating from their normal range.
(2). Battery supplied emergency lighting and communication
A central battery system consisting of lead acid cell units is provided to supply
emergency electric power, when needed, to essential items such as the power plant's
control systems, communication systems, turbine lube oil pumps, and emergency
lighting. This is essential for a safe, damage-free shutdown of the units in an emergency
situation.
(3). Transport of coal fuel to site and to storage
Most thermal stations use coal as the main fuel. Raw coal is transported from coal
mines to a power station site by trucks, barges, bulk cargo ships or railway cars.
Generally, when shipped by railways, the coal cars are sent as a full train of cars. The
coal received at site may be of different sizes. The railway cars are unloaded at site by
rotary dumpers or side tilt dumpers to tip over onto conveyor belts below. The coal is
generally conveyed to crushers which crush the coal to about ¾ inch (6 mm) size. The
crushed coal is then sent by belt conveyors to a storage pile. Normally, the crushed coal is
compacted by bulldozers, as compacting of highly volatile coal avoids spontaneous
ignition.
The crushed coal is conveyed from the storage pile to silos or hoppers at the boilers by
another belt conveyor system.
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Fly Ash Utilization
FLY ASH UTILIZATION AT KSTPS :-
• Concerted efforts have been made towards encouraging entrepreneurs for
utilizing the ash generated at Kota Thermal Power Station. 100% fly ash
utilization is expected upto March, 2009. The ash is being provided free of
cost to various Cement Industries and brick kiln owners and other
Industrialists. Pond Ash which was stored during earlier years has also
been utilized in road works. The ash utilization at Kota TPS is highest in the
Country.
• For achieving 100% Dry Fly Ash utilization KTPS has signed agreements
with Cement manufacturing companies with dedicated unit allocations. The
complete Dry Fly Ash evacuation system from each unit in 2 phases i.e. from
ESP to intermediate silo to main supplying silo near KTPS boundary has
been erected, tested, commissioned and operated by the respective Cement
companies at their own cost.
• KOTA THERMAL POWER STATION ACHIEVED 98.48% DRY FLY ASH
UTILIZATION DURING 2007-08
DRY FLY ASH UTILIZATION- ADVANTAGES
1. Minimum land requirement for ash storage.
2. Minimum water requirement for conveying of ash.
3. High ash storage density.
4. ECO friendly – less airborne / water pollution.
5. Reduction in Auxiliary Power Consumption
6.100% fly ash utilization prospects.
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SWOT Analysis
"SWOT" is an acronym which represents "Strengths", "Weaknesses", "Opportunities",
and "Threats". Note that a company's "Strengths" and its "Weaknesses" (its "flaws") are
obviously internal considerations. . In "Weaknesses", list any weaknesses along the value
chain of venture that must be strengthened to ensure success. Note that a company's
"Opportunities" and "Threats" in a company's operating environment are clearly external
considerations. Equally obvious is the fact that "Strengths" and "Opportunities" are both
positive considerations. "Weaknesses" and "Threats" are both negative considerations. To
express these relationships, it can be helpful to think of these factors in a 2 × 2 matrix
In order to do effective strategic planning, there are specific ways that this information
can be used by the company. In general, it is clear that the company should attempt -
to build its Strengths
to reverse (or disguise) its Weaknesses
to maximize the response to its Opportunities, and
to overcome its Threats.
Strengths It has the largest electricity generation capacity in Rajasthan Transmission & Distribution network of 1.1 million circuit km - the
largest in Rajasthan Potential for growth in this sector (demand exceeding supply)
Increasing focus on renewable sources of energy Government presence in this enterprise
Weaknesses Public sector players are only into generation of power Large demand-supply gap Unavailability of fuel and unwillingness of fuel suppliers to enter into bankable
contarcts Lack of necessary infrastructure to transport and store fuel, high cost risk
involved in transporting fuel
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Opportunities Huge population base Opportunities in Generation Ultra Mega Power Plants should be made into existence. Coal based plants at pithead which are untapped. Hydel power potential of 150,000 MW is untapped as assessed by the
Government of India. Renovation, modernisation, up-rating and life extension of old thermal and hydro
power plants.
Threats Competition from domestic players like NTPC Not a lucrative option for investors(ROE ) Rise in price of raw materials
Tariffs are distorted and do not cover cost
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Conclusion
-- KSTPS should emphasize on the conservation of environment, hazardous waste should
be properly eliminated but this is not the scene, some percentage of this killer waste goes
into the water of Chambal which is the drinking water source of Kota city, moreover fly
ash mixes with the surrounding air and can lead to chronic problems this need to be
checked
-- The machinery including boilers cooling pumps and other production equipments
should be regularly checked by best engineers so that they properly work and wastage of
fuel and water can be eliminated
-- The old machinery can be replaced with new and modern machinery.
-- The KSTPS can make contracts with other big players of the cement industry on the
India level like Ambuja Cement beside at Rajasthan level like Shree Cement Ltd. To
purchase their fly ash and use it as an ingredient of cement, this will help in some revenue
generation.
-- Collaboration with PSU’s like NTPC should be undertaken to have the advantage of
latest technology and knowledge workforce to improve the effectiveness and efficiency.
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References
1. http://en.wikipedia.org/wiki/Thermal_power_station
2. http://en.wikipedia.org/wiki/Deaerator
3. http://en.wikipedia.org/wiki/Economiser
4. http://en.wikipedia.org/wiki/Regenerative_heat_exchanger
5. http://www.tva.gov/power/coalart.htm
6. http://www.google.co.in/images
7. http://wapedia.mobi
8. http://images.google.co.in/images
9. http://www.rerc.gov.in
10. http://www.rvunl.com
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