ppt for ppi
Transcript of ppt for ppi
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Steam power plantLayoutBoilersPulverized coal burnersFluidized bed combustion
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Power generating unitsare mega projectsRequire huge capitalinvestmentRequire naturalresources like, fossil fuelsLarge amount of waterChanges the local ecosystemHuge Impacts on theEnvironment and Health
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Surface MiningStrip Mining
Underground Mining
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Air Quality Around the coal based plants the ambient concentrations ofSulphur Dioxide, Oxides of Nitrogen and SPM are high.
Epidemiological Studies have shown that of the area surroundingcoal based thermal plants, population living within a 2 -5 kmradius of the plant suffers from respiratory disorders .
Two other gases, carbon dioxide and ozone are emitted. The highamount of carbon dioxide emission from thermal power plantscontribute to global warming leading to climate change issignificant Ground level ozone, which is formed due tophotolytic reactions of NO x and its impacts are under study
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Fly ash contains atoxic brew of
dangerouschemicals and is thelargest contributor
to mercurypollution
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Composition of Fly ashIt contains as main chemical components SiO2
(51.4 wt%), Al2O3 (22.1 wt%) and Fe2O3 (17.2wt%; ignited weight basis). As commonlyobserved, many toxic elements and heavy metalsare highly enriched in the fly ash relative to theoriginal coal. For example, considerable amountsof Be (16.4 ppm), Cu (106 ppm), Zn (578 ppm), As(40.4 ppm), Cd (2.6 ppm), Hg (18 ppm), Pb (71ppm), and U (21.8 ppm) is found in Fly ash.
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Water slurry is used to take the ash from the powerplant to the ash pond for disposal.Water slowly seeps into the ground while carryingwith it the ash leach ate. Water may contain harmfulheavy metals like boron, which have a tendency toleach out over a period of time.When fly ash comes into contact with water, leachesinto groundwater supplies which get polluted and
unsuitable for domestic use.The release of ash pond decant into the local waterbodies- water dries up, dust nuisance, increasesturbidity, decreases primary productivity, affectsfishes and other aquatic biota
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Steam Turbine GeneratorIs a series of steam turbines interconnected to each other andthen a generator
Steam CondenserSteam enters from the turbine generator and is pumped into thebottom of the condenser, where pumps recycle the condensedsteam from the feedwater
StackReleases process emissions.
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What is a Boiler?
Introduction
• Vessel that heats water to becomehot water or steam
• At atmospheric pressure watervolume increases 1,600 times
• Hot water or steam used to transferheat to a process
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Introduction
BURNERWATER
SOURCE
BRINE
SOFTENERS
CHEMICAL FEED
FUELBLOW DOWNSEPARATOR
VENT
VENTEXHAUST GASSTEAM TOPROCESS
STACK DEAERATOR
PUMPS
Figure: Schematic overview of a boiler room
BOILER
ECO-NOMI-ZER
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Types of Boilers
1. Fire Tube Boiler
2. Water Tube Boiler
3. Packaged Boiler
4. Fluidized Bed (FBC) Boiler
5. Stoker Fired Boiler
6. Pulverized Fuel Boiler
7. Waste Heat Boiler
8. Thermic Fluid Heater (not a boiler!)
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Type of Boilers
1. Fire Tube Boiler
•
Relatively small steamcapacities (12,000kg/hour)
• Low to medium steampressures (18 kg/cm2)
• Operates with oil, gasor solid fuels
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Type of Boilers
2. Water Tube Boiler• Used for high steam
demand and pressurerequirements
• Capacity range of 4,500 – 120,000 kg/hour
• Combustion efficiencyenhanced by induceddraft provisions
• Lower tolerance forwater quality and needs
water treatment plant
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Type of Boilers
3. Packaged Boiler
OilBurner
ToChimney
• Comes in completepackage
• Features•
High heat transfer• Faster evaporation• Good convective
heat transfer• Good combustion
efficiency• High thermal
efficiency• Classified based on
number of passes
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Type of Boilers
4. Fluidized Bed Combustion(FBC) Boiler
• Particles (e.g. sand) are suspended in highvelocity air stream: bubbling fluidized bed
• Combustion at 840 ° – 950 ° C• Capacity range 0,5 T/hr to 100 T/hr• Fuels: coal, washery rejects, rice husk, bagasse
and agricultural wastes• Benefits: compactness, fuel flexibility, higher
combustion efficiency, reduced SOx & NOx
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Type of Boilers
4a. Atmospheric Fluidized BedCombustion (AFBC) Boiler
• Most common FBC boiler that uses preheatedatmospheric air as fluidization and combustion air
4b. Pressurized Fluidized BedCombustion (PFBC) Boiler
• Compressor supplies the forced draft andcombustor is a pressure vessel
•
Used for cogeneration or combined cycle powergeneration
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Type of Boilers
4c. Atmospheric Circulating FluidizedBed Combustion (CFBC) Boiler
• Solids lifted from bed,rise, return to bed
• Steam generation inconvection section
• Benefits: moreeconomical, better space
utilization and efficientcombustion
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Type of Boilers
5. Stoke Fired Boilers
a) Spreader stokers• Coal is first burnt in suspension then in
coal bed• Flexibility to meet load fluctuations• Favored in many industrial applications
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Type of Boilers
5. Stoke Fired Boilers
b) Chain-grate or traveling-grate stoker
• Coal is burnt on movingsteel grate
• Coal gate controls coalfeeding rate
• Uniform coal size forcomplete combustion
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Type of Boilers
Tangential firing
6. Pulverized Fuel Boiler• Pulverized coal powder blown with combustion
air into boiler through burner nozzles• Combustion
temperature at 1300 -1700 ° C
•
Benefits: varying coalquality coal, quickresponse to loadchanges and high pre-heat air temperatures
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LayoutDamsSelection of waterturbinesTypes of turbines
Pumped storagehydel plants
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Water from thereservoir flows dueto gravity to drivethe turbine.Turbine isconnected to agenerator.Power generated istransmitted overpower lines.
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Hydropower
Technology
Impoundment Diversion Pumped Storage
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ArchGravityButtressEmbankment or Earth
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Arch shape givesstrengthLess material(cheaper)Narrow sites
Need strongabutments
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Weight holds damin placeLots of concrete(expensive)
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Face is held upby a series ofsupportsFlat or curvedface
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Earth or rockWeight resistsflow of water
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Doesn’t require dam
Facility channelsportion of riverthrough canal orpenstock
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During Storage,water pumped from
lower reservoir tohigher one.Water released back to lower reservoir togenerate electricity.
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Operation : Two pools of WaterUpper pool – impoundmentLower pool – natural lake,river or storage reservoirAdvantages :
Production of peak powerCan be built anywherewith reliable supply of water
The Raccoon Mountain project
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Definitions may vary.Large plants : capacity >30 MWSmall Plants : capacity b/w 100 kW to 30 MW
Micro Plants : capacity up to 100 kW
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Many creeks and rivers are permanent, i.e., theynever dry up, and these are the most suitable formicro-hydro power production
Micro hydro turbine could be a waterwheelNewer turbines : Pelton wheel (most common)Others : Turgo, Crossflow and various axial flowturbines
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Types of Hydro Turbines:Impulse turbines
Pelton WheelCross Flow Turbines
Reaction turbinesPropeller Turbines : Bulb turbine, Straflo, TubeTurbine,Kaplan TurbineFrancis TurbinesKinetic Turbines
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Uses the velocity of the water to move the runnerand discharges to atmospheric pressure .The water stream hits each bucket on the runner.
No suction downside, water flows out throughturbine housing after hitting.High head, low flow applications.
Types : Pelton wheel, Cross Flow
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Nozzles directforceful streams of
water against a seriesof spoon-shapedbuckets mountedaround the edge of a
wheel.Each bucket reversesthe flow of water andthis impulse spins theturbine.
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Suited for high head,low flow sites.
The largest units canbe up to 200 MW.Can operate withheads as small as 15meters and as high as1,800 meters .
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drum-shapedelongated,
rectangular-sectionnozzle directedagainst curved vaneson a cylindrically
shaped runner“squirrel cage”blower
water flows through
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First pass : water flows from the outside of theblades to the insideSecond pass : from the inside back out
Larger water flows and lower heads than the Pelton.
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Combined action of pressure and moving water.Runner placed directly in the water stream flowingover the blades rather than striking each
individually.lower head and higher flows than compared with theimpulse turbines.
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Runner with three to sixblades.Water contacts all of the
blades constantly.Through the pipe, thepressure is constantPitch of the blades -fixed or adjustableScroll case, wicket gates,and a draft tubeTypes: Bulb turbine,Straflo, Tube turbine,Kaplan
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The turbine andgenerator are a
sealed unit placeddirectly in thewater stream.
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Straflo : The generator is attached directly to theperimeter of the turbine.Tube Turbine : The penstock bends just before or
after the runner, allowing a straight line connectionto the generatorKaplan : Both the blades and the wicket gates areadjustable, allowing for a wider range of operation
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The inlet is a scroll-shaped tube that wrapsaround the turbine's
wicket gate.Water is directedtangentially, through thewicket gate, and spiralson to a propeller shapedrunner, causing it tospin.The outlet is a speciallyshaped draft tube thathelps decelerate thewater and recover
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Best suited for siteswith high flows and
low to medium head.Efficiency of 90%.expensive to design,manufacture andinstall, but operatefor decades.
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Also called free-flow turbines.Kinetic energy of flowing water used rather thanpotential from the head.
Operate in rivers, man-made channels, tidal waters,or ocean currents.Do not require the diversion of water.Kinetic systems do not require large civil works.
Can use existing structures such as bridges, tailracesand channels.