3 October 2013

Power Generation Part-I

1) What are the sources of energy?
Ans:The sources of energy are:Sun,Wind,Water,Fossil Fuels,Nuclear energy.

2) Name the different types of power generation methods.
Ans:
  • Conventional methods: 
  • Hydro power generation
  • Thermal power generation
  • Nuclear power generation
Non-Conventional methods:
  • MHD (magneto hydro dynamic) power generation
  • Solar power generation
  • Fuel cells generation
  • Thermo electric generation
  • Thermionic converters
  • Solar cells
  • Wind power generation
  • Geo-thermal energy generation
  • Tidal power generation
  • OTEC
3) How will you classify hydro-electric plants according to nature of load?
Ans:
  1. Base load plants
  2. Peak load plants
4) What is Penstock?
Ans: Penstock is pipes of large diameter made of steel or reinforced concrete used to carry water from valve house to the water turbine.

5) What is the principle of pumped storage scheme?
Ans: The basic principle of pumped storage scheme is to convert the surplus electrical energy generated by a power plant or available in a system in off peak periods, to hydraulic potential energy, in order to generate power in periods where the peak demand on the system exceeds the total available capacity of the generating stations.

6) What are the factors to be considered while selecting a site for steam power plants?
Ans: The factors to be considered for selecting the steam power plant are as follows:
  • Nearness to the load center
  • Availability and supply of cooling water
  • Availability of coal
  • Land requirement
  • Transport facilities and Ash disposal facilities.
7) What is the function of deaerator in steam power plant?
Ans: The function of deaerator is to reduce dissolved oxygen content in the condensate i.e. in the feed water. The feed water is then pumped into boiler through economizer in which it is further heated by the heat of the flue gas passing through it on the way to chimney.

8) What are the disadvantages of steam power plants?
Ans: The disadvantages are:
  • Pollution of atmosphere due to fumes and residues from pulverized fuels.
  • High maintenance and operating cost.
  • Requirement of water in huge quantity.
  • Handling of coal and disposal of ash is quite difficult.
  • Troubles from smoke and heat from the plant.
  • Requires long time for erection and put into action.
9) What is nuclear fission?
Ans: Nuclear Fission is the process of breaking up of nuclei of heavy atoms into two nearly equal parts with release of huge amount of energy.

10) What is nuclear reactor?
Ans:In nuclear station, heavy elements such as Uranium (U235) or Thorium (Th232) are subjected to nuclear fission in a special apparatus known as reactor.

11) What are the components of nuclear reactor?
Ans: The nuclear reactor consists of the following basic components
  • Reactor core
  • Moderator
  • Control rods
  • Coolant
  • Reflector
  • Thermal shielding
  • Reactor vessel Biological shield.
12) What are the merits of nuclear power plants?
Ans: The advantages are:
  • The amount of fuel required is small; therefore, there is no problem of transportation, storage etc.
  • The demand for coal, oil and gas is reduced which are tending to rise in cost as the stocks are becoming depleted.
  • These plants need less area as compared to any other plant.
  • A 2000MW nuclear plant needs 80 acres whereas thermal stations need about 250 acres of land.
  • Most economical in large capacity.
  • The operating cost is quite low and once the installation is completed, the loading of the plant is always operated as a base load plant.
13) What are the advantages of MHD generation?
Ans: The advantages are
  • The conversion efficiency is around 50% to 60%.
  • No moving part, so more reliable.
  • Capital cost is less compared with conventional steam plants.
  • Overall generation cost is less.
  • Economic and reduced fuel consumption.
  • The closed cycle system produces power free of pollution.
  • Elimination of energy losses.
14) What is solar cell?
Ans:A solar cell is a transducer, which converts the sun’s radiant energy directly into electrical energy and is basically a semi-conductor diode capable of developing a voltage of 0.5-1 volts and a current density of 20-40 mA/sq.cm depending on the materials used and the conditions of sunlight. The solar cells operate on the principle of photo voltaic effect.Solar cell convert solar energy directly into electrical energy without any intermediate thermodynamic cycle.

15) What are the types of collectors used in solar power generation?
Ans: Types of collectors
  • Flat plate collectors
  • Focusing or concentrating collectors
  • Cylindrical parabolic concentrator
  • Paraboloids Mirror Arrays
16) What is the basic principle of wind power generation?
Ans: Winds are essentially caused by the solar heating of the atmosphere. They carry enormous quantity of energy. Wind as a source of power is very attractive because it is plentiful,inexhaustible,renewable and non-polluting. There is no depletion of scarce resources. In large portion of the world, wind blows for 320 days in a year and this gives them an advantage over sunlight in direct conversion program, operating cost of a wind mill is negligible.The ideal maximum efficiency is equal to 59% but an overall efficiency of 30% could be had due to aerodynamic and other mechanical losses. This gives a power of about 0.3KW/sq.m for a wind velocity of 10m/s.

17) What is TIDE?
Ans: TIDE is a periodical rise and fall of the water level of sea which are carried by the action of the sun and moon on the water of the earth.The main feature of the tidal cycle is the difference in water surface elevations at the high tide end, the tidal energy can be converted into electrical energy by means of a generator.

18) What is the function of moderator in nuclear power plant?
Ans: A nuclear reactor is a cylindrical stout pressure vessel and houses fuel rods of Uranium, moderator and control rods. The fuel rods constitute the fission material and release huge amount of
energy when bombarded with slow moving neutrons.The moderator consists of graphite rods which enclose the fuel rods. The moderator slows down the neutrons before they bombard the fuel rods.

19) What are the merits and demerits of tidal power generation?
Ans: The advantages of tidal power are: 
It is free from the problems of uprooting the people and disturbing the ecology balance.It is everlasting and is not influenced by the charging mood of the nature such as failure of the monsoon.No extra submerging of land is involved.
The major drawback of tidal power plants is their uneven operation.Variations in the tidal energy available through the lunar day and lunar month different from their solar counterparts prevent the tidal power from being regularly used in power systems during the periods of peak demand.

20) What is thermal efficiency?
Ans: The ratio of heat equivalent of mechanical energy transmitted to the turbine shaft to the heat of combustion of coal is known as Thermal efficiency of Steam power station.

21) What are the types of wind mills?
Ans: Wind energy conversion system are classified into two types:
  • Horizontal axis wind mills
  • Vertical axis wind mills

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