gear gear gear

facebook instagram twitter youtube linkedin issuu wikipedia tripadvisor izi.TRAVEL GoogleArtsmini

Turbina a vapore Ljungstrom



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.

Technical specifications

ManufacturerS.T.A.L. (Svenska Turbinfabriks Aktienbolaget Ljungström), Stockholm and Finspång, Sweden, 1928
Type7500/8500 kW - Blading R 30 S 65 - 48/175 A. Serial number 448
Descriptioncentrifugal counter-rotating steam turbine (Ljungström type), used in power plant for electricity production; outer rotors diameter 1700 mm
Feeding systemsupplied by superheated steam, with a maximum pressure of 14 bar
Cycle temperaturesinlet steam temperature: 350 °C normal, 380 °C maximum; condenser outlet temperature: 28 °C, 32 °C maximum
Maximum power9100 kW at 3000 rpm (maximum continuous power with overload valves open)
Control systemby means of one main supply valve and one steam control valve, with oil servomotor controlled by a centrifugal governor, provided with speed variation device (either by hand or by electric remote control); two overload valves with manual control; two security regulators to close the supply valve independently of the main control valve, when the rotation speed exceeds 10% of the normal value
Lubrication systemwith a gear pump, driven by one of the rotors by means of a worm screw, feeding the main bearings of the turbine and the speed regulator
Starting systemwith a hydraulic (oil) starter, fed by a pump driven by a small steam turbine
Condenserone horizontal condensation chamber, positioned beneath the turbine, having a surface area of ​​800 m² with 2990 brass pipes (L = 4650 mm, D = 19 mm, d = 17mm)
Condenser cooling systemfed by sea water supplied by means of centrifugal pump (for 450 liters/second, hydraulic head of 10 m) driven by an electric motor (135 hp at 1470 rpm)
Condensate extraction systemwith a centrifugal pump (hydraulic head 30 ) driven by an electric motor (23.9 hp at 1440 rpm)
Alternatortwo three-phase alternators STAL coupled in parallel, type G 65/128 D, 10700 kVA, 11000 V, freq. 50 Hz, power factor 0.7
Alternator efficiency0.95 to 7500 kW with a power factor of 0.7


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. 

Testi e immagini di Giuseppe Genchi
Sito realizzato da Pasquale Pillitteri