Turbine Expansion

One factor of turbine efficiency is depending from the clearance between rotor and casing. High temperature of turbine metal create expansion which still under control so it can not make rotor and casing touch each other.

Turbine by SIEMENS manufactured like picture beside describe how much expansion in the high pressure, intermediate and low pressure of turbine. Thrust bearing position is the point where the turbine expansion reference. The location is between high pressure (HP) and intermediate pressure (IP) of turbine. So HP turbine will be expansion to left and IP and low pressure (LP) will expansion to right. LP Turbine which furthest location from thrust bearing will get the longest of expansion.


Turbine SIEMENS if get unit trip without seal steam, can get short time for recovery unit. It means air ambient which make cold turbine metal through labyrinth seal is avoid.

Different case of in another turbine like TOSHIBA where the Unit get short outage and goes to warm start up get dilemma about water quality. If the condenser vacuum initiate to break also seal system put to shut down, water quality is hard to recovery caused by contaminated with air ambient before.

But if the short outage of unit which seal system keep in service, the turbine metal temperature is slowly to increase although ventilator valve already open when de-synchronize be initiated. The increasing the turbine metal temperature make HP expansion get worst and the turbine get no permissive for rolling and need more time for turbine turning at very low RPM by turning device .

SIEMENS and TOSHIBA is so different character.

Information about Turbine Governing System, click below this ...
http://idpowerstation.blogspot.com/2009/09/turbine-governing-system.html