Date post: | 15-Jul-2015 |
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Engineering |
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In this Presentation
• Basic of Power Generation
• Basic information on Coal/Fuel Oil
• Combustion Process
• Power Plant Cycle
• Factors affecting Efficiency
• Boilers and Turbines
• Transmission of Power and Switching
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Coal to Electricity ….. Basics
Coal
Chemical Energy
Super Heated Steam
Pollutants
Thermal Energy
Turbine Torque
Heat Loss
In
Condenser
Kinetic Energy
Electrical Energy
Alternating current in Stator
Mech. Energy
LossASHHeat
Loss
Elet. Energy
Loss
PMI Revision 00 6
Major
Energy
Sources of
India
NR
WR
SR
ER
NER
Ennore
Kudankulam
Kayamkulam
Partabpur
Talcher/Ib Valley
Vindhyachal
Korba
MAJOR ENERGY RESOURCES IN INDIA
LEGEND
Coal
Hydro
Lignite
Coastal
Nuclear
Vizag
Simhadri
Kaiga
Tarapur
Mangalore
Krishnapatnam
RAPP
53,000MW
23,000MW
1,700MWSIKKIM
MY
AN
MM
AR
CHICKEN NECK
Cuddalore
SRI LANKACOLOMBO
NEPALBHUTAN
DESHBANGLA
South Madras
Pipavav
Generation Load-Centre
Kolkata
Bhubaneswar
Patna
Lucknow
Delhi
Mumbai
Chennai
Bangalore
Bhopal
Guwahati
Jammu
Ludhiana
Jaipur
Gandhinagar
Indore
Raipur
Thiruvananthapuram
Kozhikode
Hyderabad
* Hydro Potential : 1,10,000
> 25,000MW already installed
> 19,000MW under implementation
> 66,000MW still to be exploited
* 90% coal reserves in ER & WR
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Why Coal?
Share of Coal in Power
Generation
Advantages of Coal Fuel
•Abundantly available in India
•Low cost
•Technology for Power Generation well developed.
•Easy to handle, transport, store and use
Shortcomings of Coal
•Low Calorific Value
•Large quantity to be Handled
•Produces pollutants, ash
•Disposal of ash is Problematic
•Reserves depleting fast
•India’s Coal Reserves are estimated to be 206 billion tonnes. Present consumption is about 450 million tonnes.
•Cost of coal for producing 1 unit of electricity (Cost of coal Rs 1000/MT)is Rs 0.75.
•Cost of Gas for producing 1 unit of electricity (Cost of Gas Rs 6/SMC)is Rs 1.20.
Coal
55%
Gas
10%
Diesel
1%
Hydel
26%
RES
5%
Nuclear
3%
PMI Revision 00 8
Knowing more about Coal
Coal Transportation
•Rail
•Truck
•Conveyor
•Ship
Coal production
•Surface Mining
•Underground Mining
Coal Properties
•Calorific Value
•Grade of Coal (UHV)
•Proximate Analysis
•Ultimate Analysis
•Ash and Minerals
•Grindability
•Rank
•Physical Characteristics
Coal Beneficiation
•Why?
•Processes
•Effectiveness
Coal production
•Surface Mining
•Underground Mining
Useful Heat Value (UHV) UHV= 8900-138(A+M)
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Boiler/ steam generator
Steam generating device for a specific purpose.
Capable to meet variation in load demand
Capable of generating steam in a range of operating pressure and temperature
For utility purpose, it should generate steam uninterruptedly at operating pressure and temperature for running steam turbines.
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Boiler/ steam generator
• Raw materials for design of boilers
1. Coal from mines
2. Ambient air
3. Water from natural resources (river, ponds)
o Generating heat energy
o Air for combustion
o Working fluid for steam generation, possessing heat energy
A 500MW steam generator consumes about 8000 tonnes of coal every
day
It will be considered good, if it requires about 200 cubic meter of DM
water in a day
It will produce about 9500 tonnes of Carbon di Oxide every day
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Types of Boilers
• Fire-Tube Boilers Fire-tube
boilers rely on hot gases circulating
through the boiler inside tubes that are
submerged in water. These gases
usually make several passes through
the tubes, thereby transferring their
heat through the tube walls and
causing the water to boil on the other
side. Fire-tube boilers are generally
available in the range of 20 through
800 boiler horsepower (bhp) and in
pressures up to 150 psi.
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Types of Boilers
• Electric Boilers Electric
boilers are very efficient
sources of hot water or
steam, which are available in
ratings from 5 to over 50,000
kW. They can provide
sufficient heat for any HVAC
requirement in applications
ranging from humidification
to primary heat sources.
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Types of Boilers
• Water Tube Boiler: Here the heat source is outside the tubes and the water to be heated is inside. Most high-pressure and large boilers are of this type. In the water-tube boiler, gases flow over water-filled tubes. These water-filled tubes are in turn connected to large containers called drums.
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Steaming Capacity
Large boiler capacities are often given in Tonnes of
steam evaporated per hour under specified steam
conditions
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Coal analysis
• Typical composition (Proximate analysis)
1. Fixed carbon
2. Fuel ash
3. Volatile material
4. Total Moisture
5. Sulfur
o High calorific value/ Lower calorific value (Kcal/kg)
o Hardgrove Index (HGI)
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Combustion of coal
Carbon, hydrogen, sulfur are sources of heat on combustion
Surface moisture removed on heating during pulverization.
Inherent moisture and volatiles are released at higher temperature, making coal porous and leading to char/ coke formation. (Thermal preparation stage)
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Fuel Oil
Three liquid fuels used in power plants– 1. Heavy Fuel Oil (HFO)
– 2. LSHS (Low Sulfur Heavy stock)
– 3. High speed Diesel (HSD)
Oil firing is preceded by
Lowering viscosity and increasing flowability on heating for better combustion in given turn down ratio.(125oC)
Droplet formation on atomization (by steam/ compressed air/ mechanical pressurization)
Combustion initiation by High energy spark ignition
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Combustion of reactants
Reaction rate depends on concentration of one of the reactants
Concentration varies on partial pressure of the reactants.
Partial pressure is a function of gas temperature.
Therefore, reaction rate depends on temperature and substance that enter the reaction.
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Combustion Reactions
(Carbon)
• Main reactions
2C + O2 = 2CO + 3950 BTU/lb (Deficit air)
C + O2 = CO2 +14093 BTU/lb
Secondary reactions
2CO + O2 = 2CO2 + 4347BTU/lb C + CO2 =
2CO -7.25MJ/kg
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Combustion Reactions
(Carbon)• Carbon reaction
2C + O2 =2CO [Eco =60kJ/mol]
C + O2 =CO2 [Eco2 =140kJ/mol]
reaction at 1200oC
4C + 3O2 =2CO + 2CO2 (Ratio 1:1)
Reaction at 1700oC
3C + 2O2 = 2CO +CO2 (Ratio 2:1)
It is desirable to supply combustion air at lower temperature regime in furnace
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Combustion Reaction
(H2, S)
Hydrogen reaction
2H2 + O2 = 2H2O +61095 BTU/lb
Sulfur reaction
S + O2 = SO2 + 3980 BTU/lb (undesirable)
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Coal for combustion
Anthracite
Semi-anthracite
Bituminous
Semi-Bituminous
Lignite
Peat
High CV, low VM
High CV, low VM
Medium CV, medium VM
Medium CV, medium VM
Low CV, high VM, high TM
Very low CV, high VM & TM
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Factors Affecting Thermal
Cycle Efficiency
• Initial steam Pressure
• Initial Steam Temperature
• Whether reheat is used or not, and if used reheat
pressure and temperature
• Condenser pressure
• Regenerative feed water heating