Steam Turbine

A turbine driven by steam expansion through the blades of the turbine.

Kinetic energy is generated in a series of nozzles or vanes, and the steam, issuing therefrom at a high velocity, impinges on another series of moving vanes or buckets and gives up some of its kinetic energy to them. In the ideal turbine the steam would leave the moving vanes with zero velocity and all its kinetic energy would be changed into work done on the rotating vanes. The turbine is enabled to do this by changing the momentum of the steam in its passage through the moving vanes, the change of momentum per second constituting the driving force on these vanes.

Steam turbines of type SST-6000 can be used in combined cycle and steam power plants and provides a power output from 300 to 1200 megawatts (MW).The photo shows the LP rotor for an SST5-6000 steam turbine at Muelheim plant. The turbine was delivered to the Paition steam power plant in Indonesia. Copyright Siemens AG, Munich/Berlin

The higher the main steam temperature, when accompanied by a corresponding increase in main steam pressure, the better the cycle efficiency.

In order to be able to run at higher steam temperature and pressures the turbine blades need better creep strength and improved oxidation resistance.

Historical Notes

  1. 1884 Sir Charles Parsons patents the steam turbine.
  2. 1894 Turbinia is the first steam turbine powered ship.
  3. 1908 The first steam turbine rail locomotive was built for the Officine Meccaniche Miani Silvestri Grodona Comi, Milan, Italy.

Condensing Turbine

Steam exhausts to the condenser and the latent heat of the steam is transferred to the cooling water. The condensed steam is returned to the boiler as feedwater.

Equalizing Hole

A hole in the turbine disc designed to equalize axial thrust with impulse turbines.

Leading Edge

The point where the steam enters the blade of an impulse turbine.

Overspeed Trip

Mechanism that provides absolute reliable overspeed protection by shutting off the steam supply.

Rotor

The rotating assembly enclosed within the turbine casing.

Turbine Meter

Device used to measure water consumption in industrial plants.

Vaporous Carryover

Referring to impurities carried over with the steam and then forming a deposit on turbine blades. This type of carryover is difficult to prevent.

Reference

J. Zachary, P. Kochis, R. Narula, "Steam Turbine Design Considerations for Supercritical Cycles", Coal Gen 2007


See also: Cross Compound Turbine, Engine, External Combustion Engine, Parsons, Charles Algernon, Rankine Cycle, Steam, Steam Condenser, Steam Engine, Turbine.

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Subjects: Engines


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