Ljungstrom Turbine - Graces Guide (original) (raw)

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Axial flow blades on disc of Ansaldo Ljungstrom turbine

The Ljungström turbine was a radial flow steam turbine invented and developed by Swedish brothers Birger Ljungstrom and Frederick Ljungstrom.

In this type of turbine, all of the blading revolves (rather than only half the blades as in most turbines) - one half revolves in one direction and the other half in the other, so that the relative speeds of the two sets of blading is doubled, giving a closer approximation to the optimum relation of the speed of steam and blading than is possible in the conventional type. A necessary result of this arrangement is that a Ljungstrom turbine has two output shafts, one for each set of blades. In the case of turbine generators, this incurs the cost of two generators[2]

In conventional turbines alternate rows of blades were stationary, and were located in fixed casings with flanged joints. These casings were subject to appreciable temperature gradients, giving rise to transient distortion and changes in internal clearances. These distortion effects were minimised in Ljungström turbines, offering considerable advantages, with the result that load could be applied much more quickly, ideal for peak lopping. On the downside, their construction was complex, with many parts demanding a high standard of precision machining. Assembly and dismantling were potentially much more difficult than with conventional turbines. Also, the maximum allowable length of blades was smaller than with conventional turbines, so where longer blades were needed - to accommodate higher steam volumes - they had to be accommodated using conventional axial flows (see Swansea and Milan museum photos).

The turbines were manufactured in Sweden by Svenska Turbinfabriks Aktiebolaget Ljungström, and later manufactured under licence overseas by companies including the Brush Electrical Engineering Co, Sautter-Harlé and Gio. Ansaldo and Co.

Birger Ljungström first worked on the concept in 1894, but it was not until 10 years later that he really pursued it, and theoretical calculations were undertaken by Erik August Forsberg. Manufacture of the first blade ring was entrusted to C. E. Johansson and Co. Following encouragement from Professor Stodola, Ljungström Angturbin was established in 1907.

The first (experimental) 500 kW machine was made at Lovholmen, and first ran in January 1910.

In 1910 it was resolved to build a 1000 kW 3000 rpm turbine alternator. Fredrik Ljungström was responsible for many aspects of the design and manufacture, including the adoption of the all-important conical 'expansion ring', and the mounting of the machine on its condenser, without adopting massive concrete foundations. The machine first ran in 1911, with steam at 170 psi, 660F, and gave full load steam consumption of just 8.3 lb per hph. This machine, the first production Ljungström turbine, was sold through the Brush Electrical Engineering Co to the North Metropolitan Electric Power Supply Co for installation at Willesden Power Station.

An excellent account of the development of the Ljungström radial flow turbine was presented in a Newcomen Society Paper in 1980 [3]

A 30MW Brush Ljungström turbine from Doncaster Power Station was preserved at Manchester's Museum of Science and Industry. Regrettably, this, and a number of other important power-related exhibits, were destined to fall victim to the museum's apparent wish to create empty space. More information here.

See Also

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Sources of Information

  1. ↑ [1] ephotozine image
  2. ↑ The Engineer 1918/05/17
  3. ↑ Sheriff, T. (1980). The Early Development of the Ljungström Radial Flow Steam Turbine. Transactions of the Newcomen Society, 52(1), 31–47. https://doi.org/10.1179/tns.1980.003