The modernization of aging Italian geothermal plants: the latest generation of 20 MW steam turbines

摘要

Geothermal energy has always been a major area of interest for Ansaldo Energia; in particular, extensive experience has been made in the last thirty years in the design, manufacture and installation of geothermal steam turbines, both in Italy and abroad. While the actual output of each unit depends on site conditions, the conceptual design was based on three different configurations: 5 MW, 20 MW and 60 MW. Today many Italian 20 MW geothermal plants are approaching, or have even exceeded, their expected design life: a major renovation work is therefore planned for these plants by the owner utility in the next future. In this framework, new steam turbines and generators will be supplied. Such units incorporate many distinctive features already employed on machines of the previous generation, with improved performances resulting also from the application of longer last stage blades than for the original machines, but with the same footprint and the same interfaces towards the generator, the condenser and the gas extractor system. A very tight schedule has been planned for the replacement of the existing units with the new ones, in order to minimize overall shutdown time and therefore minimize production losses.