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Chapter 6
Steam Turbines
© Springer Science+Business Media Dordrecht 2015
E. Dick, Fundamentals of Turbomachines, Fluid Mechanics and Its Applications 109,
DOI 10.1007/978-94-017-9627-9_6
Abstract The present chapter discusses the working principles and the construction forms of steam turbines, starting with an outline of their historical evolution.
The two basic types of steam turbines are analysed. These are the impulse type and
the reaction type. The chapter is also intended to formulate the general theory of
axial turbines. In particular, the crucial role of the degree of reaction is discussed.
Typical construction forms of large steam turbines for power stations and small turbines for industrial applications are illustrated. The chapter ends with a discussion
of the shaping of blades and vanes.
6.1 Applications of Steam Turbines
A steam turbine produces shaft power by means of an enthalpy drop of steam. A
special feature of steam turbines is their ability for very high power, due to the big
enthalpy drop realisable per steam mass unit. Supply conditions in modern coalfired electric power stations come to about 250 bar (25 MPa), 565 °C (supercritical).
Steam expansion to a 5 kPa vacuum provides about 1500 kJ/kg when applying one
reheat. This enables power generation in the 1000 MW order.
The working principles of steam turbines have been known since ancient times,
but practical realisation was only achieved at the end of the nineteenth century,
by Gustaf de Laval (Sweden) in 1883 and by Charles Parsons (UK) in 1884. Industrial applications started around 1920. The development of steam turbines was
mainly advanced by the use of electricity as an energy carrier. From 1920, energy
production was concentrated in electric power stations requiring high power driving
units. Steam turbine power strongly increased in the course of time. A 1 MW turbine
was a large unit in 1920. At present, units with 1000 MW power per shaft (coal)
are common, whereas the biggest turbines yield a power of 1800 MW per shaft
(nuclear) (see web sites of typical manufacturers Alstom, Siemens, General Electric
and Mitsubishi, combined with power or energy).
Worldwide, the largest part of the electricity is produced by steam turbines.
Steam is obtained by water evaporation under pressure, with solid, liquid, gaseous
or nuclear fuels. The fuel is chosen depending on economic factors and environmental restrictions. Due to the low cost of nuclear fuel on the one hand but the high
Chapter 6
Steam Turbines
© Springer Science+Business Media Dordrecht 2015
E. Dick, Fundamentals of Turbomachines, Fluid Mechanics and Its Applications 109,
DOI 10.1007/978-94-017-9627-9_6
Abstract The present chapter discusses the working principles and the construction forms of steam turbines, starting with an outline of their historical evolution.
The two basic types of steam turbines are analysed. These are the impulse type and
the reaction type. The chapter is also intended to formulate the general theory of
axial turbines. In particular, the crucial role of the degree of reaction is discussed.
Typical construction forms of large steam turbines for power stations and small turbines for industrial applications are illustrated. The chapter ends with a discussion
of the shaping of blades and vanes.
6.1 Applications of Steam Turbines
A steam turbine produces shaft power by means of an enthalpy drop of steam. A
special feature of steam turbines is their ability for very high power, due to the big
enthalpy drop realisable per steam mass unit. Supply conditions in modern coalfired electric power stations come to about 250 bar (25 MPa), 565 °C (supercritical).
Steam expansion to a 5 kPa vacuum provides about 1500 kJ/kg when applying one
reheat. This enables power generation in the 1000 MW order.
The working principles of steam turbines have been known since ancient times,
but practical realisation was only achieved at the end of the nineteenth century,
by Gustaf de Laval (Sweden) in 1883 and by Charles Parsons (UK) in 1884. Industrial applications started around 1920. The development of steam turbines was
mainly advanced by the use of electricity as an energy carrier. From 1920, energy
production was concentrated in electric power stations requiring high power driving
units. Steam turbine power strongly increased in the course of time. A 1 MW turbine
was a large unit in 1920. At present, units with 1000 MW power per shaft (coal)
are common, whereas the biggest turbines yield a power of 1800 MW per shaft
(nuclear) (see web sites of typical manufacturers Alstom, Siemens, General Electric
and Mitsubishi, combined with power or energy).
Worldwide, the largest part of the electricity is produced by steam turbines.
Steam is obtained by water evaporation under pressure, with solid, liquid, gaseous
or nuclear fuels. The fuel is chosen depending on economic factors and environmental restrictions. Due to the low cost of nuclear fuel on the one hand but the high