ENERGY CONVERSION IN STEAM TURBINE

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  • Here we study how a turbine convert the high pressure & temperature steam energy in to mechanical energy.
  • A steam turbine basically consists of two elements or sets of elements.
    • Nozzel
    • Curved blade
  • Steam turbines are used to convert the heat energy of the steam into mechanical energy.
  • If the steam turbine drives a generator, then this mechanical energy will be converted into electrical energy.
  • The steam turbine is a very simple machine with few moving parts.
  • It is not unusual for a steam turbine to run for more than a year without shutdown. 
  • While very reliable, the steam turbine generator is a complex machine with many components and supporting systems.
  • The power plant is often described as an energy conversion factory in which the chemical energy in the fuel is converted into electrical energy.
  • For conversion of chemical energy of fuel following block diagram is shows:-

energy conversion in Thermal power plant

  • The function of the steam turbine is to convert the high pressure and temperature steam energy in to mechanical energy.
  • The conversion of energy in the turbine actually occurs in two steps.
  • First, the heat energy in the steam is converted into kinetic energy of a steam jet by nozzles.
  • Second, the steam jets are used with buckets or blades mounted on a rotor to produce a mechanical force and torque
  1. In a steam turbine high pressure and  high temperature steam  (steam having high enthalpy) is expanded in the nozzles (stationary blades).
  2. Where the kinetic energy is increased at the expense of pressure energy (increase in velocity due to decrease in pressure).
  3. The kinetic energy is converted into mechanical energy (rotation of a shaft  increase of torque or speed) by impulse and reaction principles.
  4. The impulse principle consists of changing the momentum  of the flow, which is directed to the moving blades by the stationary blades. 
  5. The jet’s impulse force pushes the moving blades forward. The reaction principle consists of a reaction force on the moving blades due to acceleration of the flow as a result of decreasing cross-sectional area.

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