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Turbine stages in Power Plant

Stages of Turbine in Power Plant

The turbine has one single flow High Pressure turbine, one double flow Intermediate Pressure, and one double flow Low Pressure turbine.

HP: High-Pressure Turbine
IP: Intermediate Pressure Turbine
LP: Low-Pressure Turbine

High-Pressure Turbine:

  • The construction of High Pressure turbine is barrel type. This avoids mass accumulation due to the absence of flanges. The inner casing carries the guide blades and is axially split and supported.
  • The space between the inner and outer shell is sealed from the neighboring space by sealing rings. 
  • It consists of 17 reaction stages. and exhaust steam pressure with 44 bar. the inlet steam temperature is 535ºC.
  • As the inner casing is not subjected to large pressure drop the joint flange and bolts are designed for the less stringent condition.
  • In this inner casing is fixed in the horizontal and vertical planes in the outer casing so that it can freely expand radially in all direction and axially from a fixed point when heating up while maintaining eccentrically.
  • Due to the absence of high thermal stresses the barrel construction permits rapid start-up and higher rates of load changes are done.
  • This type of turbine is easy at the time of opening.

Intermediate Pressure Turbine:

  • The Intermediate Pressure casing is split horizontally and a double flow and double shell construction. this is with inner casing carrying the guide blades and supported by kinematically within the outer casing.
  • This type of construction is flexibility for choosing the locations of the bleed steam point to suit the thermal efficiency.
  • This has 12 reaction stages per flow. it has steam pressure stop value inlet around 39 bar. its inlet steam temperature is about 338 degrees.
  • The reheated steam enters the inner casing through the top and bottom.
  • In this hydraulic turning gear blades are located on the coupling of the IP rotor.

Low-Pressure Turbine:

  • This type of casing is of triple shell fabricated construction. the outer casing consists of the front and rear and ends walls.
  • In this it present with 6 reaction stages per flow. this exhaust steam pressure about 0.09 bar. The steam temperature exhaust around 45 degrees.
  • Kinematically support is given to the shell inner casing at each end by two support arm resisting on the member of the outer casing.
  • The inner shell of inner casing carries the guide blade of the first ideal blade carrier which is used to constitute the remaining stages of the turbine. and this is bolted to the middle inner outer casing.
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