- The plant where electrical energy is generated is called generating stations or power plants.
- Electrical energy is generated at bulk value.
- Electrical energy generated at 11KV.
Hydroelectric power Plants
- A power plant which utilizes the potential energy of water at a high level for the generation of electrical energy.
- These plants are located in hilly areas.
Elements of Hydro-electric power plants
- Dam is made from Concrete.
- Water is collected from the catchment area.
- Reservoir stores the water. It may be natural or artificial.
- Spillway is constructed to act as a safety value.
- Water is taken to water turbine through a huge steel pipe known as
- Surge Tank (open from top) is built just before the valve house and protects the penstock.
- Water turbines convert the energy of falling water into mechanical energy.
- The water after having done its useful work in the turbine is discharge to the tail race.
Types of Turbines
- Impulse Turbines are used for high head. (above 200m). example of Impusle turbine is pelton wheel.
- Reaction turbines are two types
(a) Francis turbine is used for low to medium head (head from 30m to 200m)and
(b) Kaplan turbine is used for low heads and large quantities of water.(head less than 30 m)
- Classification of Hydroelectric power plants according to Availability of water head
Low Head:- below 30 metres
Medium Head:- above 30 metres and below 300 metres
High Head :- above 300 metres.
Steam/Thermal power plants
- A generating station, which converts heat energy of coal combustion into electrical energy is known as Steam power plants.
- Steam coal used is boiler in as a fuel.
Coal Used in Power Plant
|Sr. No.||Particular||Calorific Value||Ash Content|
|1||Lignite Coal||5,000 kcal/kg||8%|
|2||Bituminous Coal||7,600 kcal/kg||6.5%|
|3||Anthracite Coal||8,500 kcal/kg||5%|
Parts of Thermal plants
- Boiler is a vessel where water is converted into steam. Coal combustion is done in boiler. Boiler is divided into types (a) fire tube boiler (b) water tube boiler.
- Pulveriser crushes the coal into fine particles.
- Superheater converts saturated or wet steam into superheated steam.
- Economiser: – The feed water is fed to the economiser before supplying to the boiler. It saves the fuel consumption.
- Air preheater increases the temperature of the air supplied for coal burning by deriving heat from flue gases.
- Condensers:- A condenser is a device which condenses the steam at the exhaust of turbine. There are two types condensers Jet condenser and Surface condenser.
Nuclear Power Plant
- A generating power plant in which nuclear energy is converted into electrical energy .
Main parts of nuclear power plant
- Nuclear reactor is an apparatus in which nuclear fuel is subjected to nuclear fission.
- Nuclear fuels are Uranium – 235 (U-235), Uranium – 233 (U-233), PU-239.
- Reactor core contains a number of fuel rods made of fissile material.
- Moderator: – hydrogen, Lithium, Berylium, Boron, Carbon, Nitrogen, Oxygen and Heavy Water.
- Control Rods are made of boron-10, cadmium, or hafnium.
- Coolant:- Air, Helium, Hydrogen, and Carbon dioxide, water, liquid metals( sodium and potassium.)
- Water is used both as coolant and moderator.
Economics of Power Generation
- Connected load: – all the equipments connected to supply system.
- Maximum demand :– greatest demand of load on the power station
- Demand factor:– maximum demand to connected load
- Demand factor always less than one (or unity)
- Average load: – average of loads is occurring on the power station in a given period.
- Load factor: – average load to the max. Demand.
- Load factor is less than unity.
- Diversity factor: – sum of individual max. Demand to the max. demand on the power station.
- Diversity factor will always be greater than one.