Prevention of Steam Turbine Blade Erosion Using Stator Blade Heating

Abstract

Previous work on the phenomenon of the erosion of the moving blades in steam turbines is reviewed, which has shown that this is due to the accumulation of coarse water on the stationary blades. The basic physics of the accumulation is considered and the conclusion is drawn that this is due to condensation. This can occur even on adiabatic blading, but is expected to be particularly prevalent on blades whose interior is at a reduced pressure (and hence temperature) for suction purposes. Tests are reported on the heating of a single blade mounted in a steam tunnel downstream of a small steam turbine. The turbine exhaust could be arranged to be either wet or superheated. These tests showed that condensation on the blade could be prevented using only small amounts of heating. Methods of applying this system to full size turbines are considered and preliminary economic effects estimated, with encouraging results.