Steam turbine and its types


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a brief detail of steam turbine,its kinds,parts and working.

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Steam turbine and its types

  1. 1. A machine that transforms energy from thermal, electrical or pressure form to mechanical form prime mover gradual change of momentum
  2. 2. Heat energy of the high pressure steam is converted into kinetic energy Change direction of steam issuing from the nozzle
  3. 3. Single cylinder turbines are the one which have all the stages enclosed in one cylinder while in multi cylinder turbines the stages are accommodated in more than one cylinders, say two or three. Flow in these can be single flow, double flow, cross flow or reversed flow.
  4. 4.  Radial flow turbine incorporates two shafts end to end and can be of suitably small sizes.  Radial flow turbines can be started quickly and so well suited for peak load and used as stand by turbine or peak load turbines. These are also termed as
  5. 5.  In radial flow turbines the steam is injected in middle near shaft and steam flows radially outwards through the successive moving blades placed concentrically.  In radial flow turbines there are no stationary blades so pressure drop occurs in moving blade passage.  Concentric moving blades rings are designed to move in opposite directions.
  6. 6.  The steam is the nozzle directs steam tangentially into buckets at the periphery of single wheel and steam reverses back and re-enters other bucket at its’ periphery.  This is repeated several times as steam follows the helical path.  Tangential flow turbines are very robust but less efficient.
  7. 7.  Steam flows along the axis of turbine over blades.  These axial flow turbines are well suited for large turbo generators and very commonly used presently.
  8. 8. The force because of change in tangential component of velocity of fluid which may be due to change in direction or magnitude. impulse  The steam is first made to flow through nozzle.  Then the steam impinges on the turbine blades.  After impinging, steam glides over the concave surface of the blades and finally, leave the turbine.
  9. 9.  It is a circular guide mechanism.  It regulates the flow of steam.  It is kept close to the blades, in order to minimize the losses due to windage.
  10. 10.  These consist of a circular disc fixed to a horizontal shaft.  The steam jet impinges on the buckets, which move in the direction of the jet.  This movement of the blades makes the runner to rotate.
  11. 11.  It is air-tight metallic case, which contains the turbine runner and blades.  It controls the movement of steam from the blades to the condenser.  It is essential to safegaurd the runner against any accident.
  12. 12.  The pressure of steam jet is reduced in the nozzle and remain constant while passing through the moving blades.  The velocity of steam is increased in the nozzle, and is reduced while passing through the moving blades.
  13. 13.  The steam enters through a section of curved blades in a fixed position.  The steam then enters the set of moving blades and creates enough reactive force to rotate them.  The steam exits the section of rotating blades.  The direction of rotation.
  14. 14.  The water enters the guide case of the turbine with high potential energy and relatively low kinetic energy.  The potential energy, which is a function of the pressure difference between the runner inlet and exit, causes the fluid to flow through the runner buckets.  As the fluid flows over the curved surface of the runner buckets, the fluid velocity on one side of the bucket is higher than on the opposite side.
  15. 15.  This difference in velocity on the surfaces of the bucket causes a pressure differential across the bucket which exerts a force on the bucket.  This force at its respective radius in the runner, the revolving part, then causes the runner to restore and impart mechanical energy to the turbine shaft.
  16. 16.  It is an air-tight metallic case, in which the steam from the boiler, under high pressure & temperature.  This casing is designed in such a way that steam enters the fixed blades with a uniform velocity.
  17. 17.  It is mechanism, made up with the help of guide blades, in the form of a wheel.  This wheel is, generally fixed to casing; that is why these guide blades are called
  18. 18.  Allow the steam to enter the runner without shock.  Allow the required quantity of steam to enter the turbine.
  19. 19.  The turbine runners consists of runner blades fixed to a shaft or rings.  The surface of the turbine runner is made smooth to minimize the frictional looses.
  20. 20.  The steam, after passing through runner, flow into the condenser through a tube called  In case of its absence, steam eddies are caused.
  21. 21.  The pressure in a reaction turbine is reduced in fixed blades as well as in moving blades.  The velocity of steam is increased in the fixed blades and is reduced while passing through the moving blades.
  22. 22. Rankine cycle is a thermodynamic cycle derived from Carnot vapour power cycle for overcoming its limitations.
  24. 24. High pressure water supplied by feed pump is heated and transformed into steam with or without superheat as per requirement. This high pressure and temperature steam is sent for expansion in steam turbine. Heat added in boiler, for unit mass of steam. QSUPPLY = (h2 – h1) Steam available from boiler is sent to steam turbine, where it's adiabatic expansion takes place and positive work is available. Expanded steam is generally found to lie in wet region. Wturbine = (h2 – h3)
  25. 25. Heat rejection process occurs in condenser at constant pressure causing expanded steam to get condensed into saturated liquid at state 4. Qrejected = (h3 – h4) Condensate available as saturated liquid at state 4 is sent to feed pump for being pumped back to boiler at state 1. Wpump = (h1 – h4)