The turbine Ljungström owes its name to the Swedish engineers Birger and Fredrik Ljungström who patented it in 1908. This turbine type was produced by S.T.A.L. (Svenska Turbinfabriks Aktienbolaget Ljungström) which they founded in 1913 and by other foreign companies under license, such as Ansaldo in Italy. Its uniqueness is that it is a multi-stage bi-rotary centrifugal steam turbine. It consists of two discs of proper configuration facing each other, connected with two independent counter-rotating shafts. Crowns of blades are connected to the disks and the steam is introduced into the central compartment through hollow shafts and flows through the vanes of the two discs in ordered succession towards the periphery. The bi-rotary turbines found large use in fixed installations for the production of electricity, with some applications also in railway engineering because of their favorable mass-to-power ratio. The limit to the number of radial stages, the need to adopt two separate electric machines and the growing demand for more powerful turbines determined the decline of the bi-rotary turbines in favor of the traditional type since the end of the '50s. In 1928, his turbine was fitted in the former power plant Alessandro Volta in Palermo (Siscily) and remained in service up to 1952, feedding electricity to a large parte of the city. The power plant (founded in 1898 and closed in 1952), has been equipped with two steam turbines: the Ljungström-STAL (9100 kW) and a Zoelly-type manufactured by Escher Wyss (5450 kW) since 1922.
This turbine was fitted in the former power plant Alessandro Volta in Palermo (Siscily), in 1928, and remained in service up to 1952, feedding electricity to a large parte of the city.
