Table of Contents
A steam turbine is a device which converts thermal energy of steam into mechanical energy. This mechanical energy is generally used further to generate electricity. It is invented by sir Charles Parsons in 1884.
Steam Turbine
Types of steam turbines
They are basically classified into two types
- Impulse Turbine
- Reaction Turbine
A turbine composed of blades alternating with fixed nozzles is called an impulse turbine, Curtis turbine, Rateau turbine, or Brown-Curtis turbine.
A turbine composed of moving nozzles alternating with fixed nozzles is called a reaction turbine or Parsons turbine.
Energy losses in steam turbine
It has following major energy losses
- Radiative heat loss due to improper insulation
- Steam pressure loss at regulating valves and pipes
- Mechanical friction loss at bearings and other surfaces
- Leakage of steam
- Friction losses in nozzles
- Friction losses in blades
Failure of steam turbine
It can fail under following circumstances
- Over speeding of turbine
- Low condenser vacuum
- Lubricating system failure
- High vibrations in turbine
Advantages of steam turbine
They have following advantages
- They have high reliability especially in the cases where sustained high-power output is needed
- They have less vibrations when compared to reciprocating engines
- They require less mass flow rates compared to gas turbines
- They have very high power to weight ratio when compared to reciprocating engines
- Thermal efficiency is usually high compared to reciprocating engines
- Since it is a rotary engine hence it is more suitable to drive an electricity generator
Disadvantages of steam turbines
They have following disadvantages
- They are less responsive to change in power demand compared to reciprocating engines
- They take long startup time compared to gas turbines and reciprocating engines
- In part load operations steam turbine is less efficient than reciprocating engine
Steam turbine manufacturers
Following are some steam turbine manufacturers worldwide
- Toshiba
- Mitsubishi Heavy Industries
- Doosan Škoda Power
- General Electric
- Alstom
- Bharat Heavy Electricals Limited
- Siemens
- Dongfang Electric
- Shanghai Electric
- Harbin Electric
References:
Image source: By Александр Ситенький (Alexander Seetenky) – CPI BalNpp(The Centre of the Public Information Balakovo NPP), CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11616298
Losses & failures: https://www.nuclear-power.net/nuclear-power-plant/turbine-generator-power-conversion-system/what-is-steam-turbine-description-and-characteristics/
Impulse and reaction turbine: https://en.wikipedia.org/wiki/Steam_turbine