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Oil-free magnetically levitated turbine under construction

Siemens hands over first oil-free steam turbine to Vattenfall. Siemens has delivered for the first time a steam turbine in the capacity range up to 10 megawatts (MW) that operates almost entirely without lubricants. The bearing systems consist of completely oil-free, air-cooled, electromagnetic bearings. The valve actuators operate with only a minimum oil supply and are controlled via software-controlled electric motors. The trial run of the first turbine equipped with magnetic bearings was successfully completed in Vattenfall’s lignite-fired Jänschwalde steam power plant, located in the southeast of the German state of Brandenburg, after which the model SST-600 steam turbine was officially handed over to Vattenfall. The turbine has been running reliably in regular full-load operation since February 2015, at speeds of up to 5,700 rpm. It is used as a feedwater pump drive.

Steam turbines equipped with magnetic bearings are more environmentally friendly, as they use nearly no oil, and also offer substantially better fire protection. The oilfree turbine is therefore particularly interesting for customers with highly stringent requirements for operating safety and reliability, such as in the oil and gas industry, or for use in offshore applications on drilling platforms. As the rotor so to speak “floats” without any contact with the bearings and is not supported by a film of oil, there is no longer any wear or friction resistance present, meaning that the efficiency of the steam turbine can, as a result, be increased by up to one percent.

Key customer benefits of oil-free steam turbines:

  • Optimum fire protection
  • Higher efficiency (up to 1% higher) due to lower frictional resistance
  • Lower maintenance expenditure due to wear-free bearing and online diagnosis using the bearing

Potential areas of application for oil-free steam turbines

  • Oil & gas industry, e.g. oil and natural gas pumping and processing
  • Offshore applications, e.g. drilling platforms
  • Industries with high fire hazards, such as the chemical industry, petrochemical industry, metallurgy, mining, pulp and paper industry, refineries
  • Industries with stringent environmental requirements, such as near drinking water catchment areas

Reference data for SST-600 with magnetic bearing and Jänschwalde power plant:

  • Feedwater pump drive turbine with an output of 10 MW
  • Speed: 3,600 to 5,700 rpm, prototype operation with 5,000 to 5,500 rpm
  • Main steam: temperature 535°C, pressure 36 bar
  • The Vattenfall Jänschwalde power plant is one of the largest power plants in Germany and supplies electric power and district heat
  • Installed capacity: 3,000 MWe and 348 MWth (6x 500 MW blocks)

Research and development partners

  • Close cooperation of the Zittau/Görlitz University of Applied Science with construction of a magnetic bearing test bed and joint research for qualification
  • Siemens Process Industry and Drives and Schaeffler AG in development of magnetic bearings and auxiliary bearings
  • The Vattenfall Jänschwalde power plant is one of the largest power plants in Germany and supplies electric power and district heat