basic mechanical engineeering- power plants

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M.S.STEVEAssistant ProfessorDept. of Mechanical EngineeringAmal Jyothi College of Engineering, Kanjirapally.POWER PLANTS

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Definition of Power Plant The assembly of equipments that produces mechanical energy utilizing the available energy source and converting it to electrical energy is known as a power plant2M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Classification

Hydro-electric Power PlantThermal (Steam) Power PlantDiesel Engine Power PlantNuclear Power PlantGas Turbine Power Plant3M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Hydraulic Power Plant

Plants used to produce electric power from water are known as hydro electric power plantsThis Power plants utilize the potential energy and Kinetic energy of water as the source of energy for power generation.KE & PE of water is converted into mechanical power by using prime mover Hydraulic Turbines.This mechanical energy is used to run an electric generator which is directly coupled to the shaft of the turbine.

4M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Main Elements Storage Reservoir Natural or artificial.Dam Masonry dams, wooden dams, steel damsWaterways canal, penstock, tunnelControl elements gates, valves, trash rack etcSurge Tank additional storage space between main reservoir and power house. Also controls pressure variations from rapid changes in rate of flow of water through penstockPower HouseWater TurbinesGenerator


Hydraulic Power Plant - General Layout



AdvantagesOperating cost is minimum compared to other power plants as no fuel is usedLow maintenance costMan power required for the operation is lowNo air pollution and safety problemsRapid fluctuating loads can be served economicallyLife of more than 50 years.8M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

DisadvantagesHigh initial cost.Power generation not steady and reliable.Long distance transmission required Cost of power transmission high.Long time needed for planning and erection(10 to 15 years).9M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Steam Thermal Power Plant

A Steam thermal power plant converts the chemical energy of the fossil fuels (coal,oil,gas) into mechanical/electrical energyIn India, coal using as the main fossil fuel.10M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Main systems of steam thermal plant

Fuel system coal and ash circuitAir and gas circuitFeed water systemCooling water systemBoiler HousePrime mover and Generator systemControl and Instrumentation System



Components of steam thermal plantBoilerSteam turbineGeneratorCondenserCooling towersCirculating water pumpBoiler feed pumpEconomiser

Super heaterRe heaterAir heaterBoiler chimneyWater treatment plantCoal millControl room


Advantages Less capital costConstruction time is lowPower generation not dependent on natures mercyPower plant can be located near industrial areas, so transmission cost will be less14M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Disadvantages Power generation cost is highPart load efficiency is lessFuel transportation and handling is difficult.PollutionAsh handling is difficultLife time of 20-25 years.15M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Diesel Engine Power Plant

Utilizing diesel for the power generation.Capacity of plant 2 to 50 MWMostly used as a standby power plantUses Small power capacity, for small towns, continuous power generation, peak load plant, mobile power plant16M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

ComponentsEngine- generally a 2 stroke engineAir supply systemExhaust systemFuel systemCooling systemLubricating systemStarting system- compressed air system(20kgf/cm2)Governing system- varying fuel supply



AdvantagesMore efficient for small capacity power generation than thermal plant.Layout, design and construction of buildings and foundations easier and less expensiveQuickly started up and brought into service.Full automation possible at low capital cost.No problem of fuel handling and waste disposalLess space required19M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

DisadvantagesSize is limited and very large capacities are not possible.Life is very less.Generates heavy noiseHigh repair and maintenance costHigh lubrication cost


Nuclear power plantUse atomic energy for power generationHeat energy liberated using nuclear reaction.Heat produced by 1 kg of uranium = Heat produced by 4500 tones of coal.


Types of conventional reactorsPressurized water reactor (PWR)

Boiling water reactor (BWR)


Conventional Reactor....Pressurized water reactorThe most safe and reliable technology available

Ordinary water used both for coolant and moderator

High pressure of 150atm used to prevent boiling inside the reactor

Using high pressurized hot water, steam is generated in secondary loop (called steam generator)

Thermal efficiency of about 30%


Pressurized water reactor...


Reactor systems used..1Pressurized water reactor


Conventional Reactor....Boiling water reactor

Ordinary water used as both coolant and moderator

Steam is directly generated inside the reactor core

Pressure inside the reactor is around 75atm

Thermal efficiency is about 35%

But maintenance cost more than PWREg:- Tarapur Power station26M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

Boiling water reactor


Reactor systems used..2Boiling water reactor


AdvantagesMore economical compared to thermal plants.No problem of fuel transportation, storage and handling , ash handlingLow man power required Cost of operation reduced.Less space occupied than thermal plant.29M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

DisadvantagesDanger of nuclear radiation.Disposal of radio active wastesPart load operation is inefficient.Capital cost of small sized plants is high.30M.S.Steve/ Assist. Professor/ Dept. of ME/ AJCE

basic mechanical engineeering- power plants

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