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
Where:-
L = Length of Turbine
α = coefficient of thermal expansion
ΔT= Difference of temperature.
