29 September 2023

Anchor Points of Steam Turbine | Turbine Fundamentals and Basics | Basic Aspects of Steam Turbine Maintenance Part#3 | Content-19

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Anchor Points

Anchor Points of Steam Turbine:-
1.) Purpose of Anchor Point:-  Taking care of thermal expansions and contractions of the machine during thermal cycling.

The fixed points of the turbine are as follows:

  • The bearing housing between the IP and LP turbines.
  • The rear bearing housing of the IP turbine.
  • The longitudinal beam of the I.P turbine.
  • The thrust bearing in rear bearing casing of H.P turbine.
2.) What IS Anchor Point:-
  • Anything when heated will expand. Same is true for Turbine rotors and Casings.
  • Problem with rotors is more complex as it is also subjected to the axial thrust also.
  • To allow their controlled motion during operation and to prevent any eventuality between rotor and casing they are required to be anchored.
  • Rotors are anchored at Bearing no 2(between HP &IP) by means of thrust bearing. In some Turbines they are also anchored at free end.
  • Thrust bearing( Anchor point) is always located near High temperature end to minimize the differential expansion.
  • Casings which are connected together by means of pedestals and keys have LPT front as the anchor point.
  • It is to be noted that rotor rests on the bearings and bearings further rests on the pedestals.
  • The pedestals can be moving / sliding or can be fixed. When it is sliding it carries bearing along with it which further carries rotor along with it.
3.) Total Expansion of turbine:-

Total Expansion of Turbine can be calculated which is appx. Equal to LαΔT


L = Length of Turbine

α = coefficient of thermal expansion

ΔT= Difference of temperature.



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