Steam turbine stage modernisation in front of the extraction point

The paper presents modernisation of the steam turbine stage situated in front of the turbine extraction point, based on a 225 MW turbine LP stage as an example. The modernised design is intended to better control the steam flow in this area. In the presented design a special ring is used to drive the steam leakage flow directly to the heat exchanger. The performed experiments and numerical analyses confirmed measurable exploitation and efficiency advantages of the introduced modernisation. So far, it has been successfully applied in a number of turbines working in inland power plants, but its use can be easily extended, without need for further modification and without advantage loss, to marine turbines, especially those used as main propulsion in sea-going vessels.