Compact Diaphragm Turbine Technology and Its First Application in a Turbine Retrofit

The merger between the Power Generation divisions of ABB and Alsthom in 1999, has resulted in the present day Alstom Steam Turbine Retrofit Business being the only supplier who can offer both impulse (disc and diaphragm) and reaction (drum rotor) turbine retrofit solutions across the entire product power range. The impulse and reaction turbine technologies both possess design features that are aimed at achieving the best evaluated performance for retrofit turbine solutions. Alstom has now combined service proven features from these two technologies to form the new Compact Diaphragm steam turbine technology. This will allow turbine retrofit design solutions to be optimised to levels beyond that possible with either of the contributing technologies. The Compact Diaphragm design features are described in this paper, together with the validation of the new technology. The first application entered service in June 2007 in the retrofitted HP cylinder of a G3 HP turbine in USA and is also described in this paper.